Title 49—Transportation--Volume 1
PART 178—SPECIFICATIONS FOR PACKAGINGS
§ 178.57   Specification 4L welded insulated cylinders.
(a) Type, size, service pressure, and design service temperature. A DOT 4L cylinder is a fusion welded insulated cylinder with a water capacity (nominal) not over 1,000 pounds water capacity and a service pressure of at least 40 but not greater than 500 psig conforming to the following requirements:
(1) For liquefied hydrogen service, the cylinders must be designed to stand on end, with the axis of the cylindrical portion vertical.
(2) The design service temperature is the coldest temperature for which a cylinder is suitable. The required design service temperatures for each cryogenic liquid is as follows:
(b) Material. Material use in the construction of this specification must conform to the following:
(1) Inner containment vessel (cylinder). Designations and limiting chemical compositions of steel authorized by this specification must be as shown in table 1 in paragraph (o) of this section.
(2) Outer jacket. Steel or aluminum may be used subject to the requirements of paragraph (o)(2) of this section.
(c) Identification of material. Material must be identified by any suitable method.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart and to the following requirements:
(1) No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. The shell portion must be a reasonably true cylinder.
(2) The heads must be seamless, concave side to the pressure, hemispherical or ellipsoidal in shape with the major diameter not more than twice the minor diameter. Minimum thickness of heads may not be less than 90 percent of the required thickness of the sidewall. The heads must be reasonably true to shape, have no abrupt shape changes, and the skirts must be reasonably true to round.
(3) The surface of the cylinder must be insulated. The insulating material must be fire resistant. The insulation on non-evacuated jackets must be covered with a steel jacket not less than 0.060-inch thick or an aluminum jacket not less than 0.070 inch thick, so constructed that moisture cannot come in contact with the insulating material. If a vacuum is maintained in the insulation space, the evacuated jacket must be designed for a minimum collapsing pressure of 30 psig differential whether made of steel or aluminum. The construction must be such that the total heat transfer, from the atmosphere at ambient temperature to the contents of the cylinder, will not exceed 0.0005 Btu per hour, per Fahrenheit degree differential in temperature, per pound of water capacity of the cylinder. For hydrogen, cryogenic liquid service, the total heat transfer, with a temperature differential of 520 Fahrenheit degrees, may not exceed that required to vent 30 SCF of hydrogen gas per hour.
(4) For a cylinder having a design service temperature colder than minus 320 °F, a calculation of the maximum weight of contents must be made and that weight must be marked on the cylinder as prescribed in § 178.35.
(5) Welding procedures and operations must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter). In addition, an impact test of the weld must be performed in accordance with paragraph (l) of this section as part of the qualification of each welding procedure and operator.
(e) Welding. Welding of the cylinder must be as follows:
(1) All seams of the cylinder must be fusion welded. A means must be provided for accomplishing complete penetration of the joint. Only butt or joggle butt joints for the cylinder seams are authorized. All joints in the cylinder must have reasonably true alignment.
(2) All attachments to the sidewalls and heads of the cylinder must be by fusion welding and must be of a weldable material complying with the impact requirements of paragraph (l) of this section.
(3) For welding the cylinder, each procedure and operator must be qualified in accordance with the sections of CGA Pamphlet C-3 that apply. In addition, impact tests of the weld must be performed in accordance with paragraph (l) of this section as part of the qualification of each welding procedure and operator.
(4) Brazing, soldering and threading are permitted only for joints not made directly to the cylinder body. Threads must comply with the requirements of paragraph (h) of this section.
(f) Wall thickness. The minimum wall thickness of the cylinder must be such that the calculated wall stress at the minimum required test pressure may not exceed the least value of the following:
(1) 45,000 psi.
(2) One-half of the minimum tensile strength across the welded seam determined in paragraph (l) of this section.
(3) One-half of the minimum tensile strength of the base metal determined as required in paragraph (j) of this section.
(4) The yield strength of the base metal determined as required in paragraph (l) of this section.
(5) Further provided that wall stress for cylinders having longitudinal seams may not exceed 85 percent of the above value, whichever applies.
(6) Calculation must be made by the following formula:
(g) Heat treatment. Heat treatment is not permitted.
(h) Openings in cylinder. Openings in cylinders must conform to the following:
(1) Openings are permitted in heads only. They must be circular and may not exceed 3 inches in diameter or one third of the cylinder diameter, whichever is less. Each opening in the cylinder must be provided with a fitting, boss or pad, either integral with, or securely attached to, the cylinder body by fusion welding. Attachments to a fitting, boss or pad may be made by welding, brazing, mechanical attachment, or threading.
(2) Threads must comply with the following:
(i) Threads must be clean-cut, even, without checks and cut to gauge.
(ii) Taper threads to be of a length not less than that specified for NPT.
(iii) Straight threads must have at least 4 engaged threads, tight fit and calculated shear strength at least 10 times the test pressure of the cylinder. Gaskets, which prevent leakage and are inert to the hazardous material, are required.
(i) Pressure testing. Each cylinder, before insulating and jacketing, must successfully withstand a pressure test as follows:
(1) The cylinder must be tested by the proof pressure, water-jacket, or direct expansion test method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of two (2) times service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2. Determination of expansion properties is not required.
(4) There must be no evidence of leakage, visible distortion or other defect.
(j) Physical test. A physical test must be conducted to determine yield strength, tensile strength, and elongation as follows:
(1) The test is required on 2 specimens selected from material of each heat and in the same condition as that in the completed cylinder.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width not over 1 1/2 inches, a gauge length of 2 inches with width not over 1 1/2 inches, or a gauge length at least 24 times thickness with a width not over 6 times thickness (authorized when cylinder wall is not over 1/16 inch thick).
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within one inch of each end of the reduced section.
(iii) When size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold by pressure only, not by blows. When specimens are so taken and prepared, the inspector's report must show in connection with record of physical tests detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic expansion of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on the elastic modulus of the material used. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
(k) Acceptable results for physical tests. Physical properties must meet the limits specified in paragraph (o)(1), table 1, of this section, for the particular steel in the annealed condition. The specimens must show at least a 20 percent elongation for a 2-inch gage length. Except that the percentage may be reduced numerically by 2 for each 7,500 psi increment of tensile strength above 100,000 psi to a maximum of 5 such increments. Yield strength and tensile strength must meet the requirements of paragraph (o)(1), table 1, of this section.
(l) Tests of welds. Welds must be tested as follows:
(1) Tensile test. A specimen must be cut from one cylinder of each lot of 200 or less, or welded test plate. The welded test plate must be of one of the heats in the lot of 200 or less which it represents, in the same condition and approximately the same thickness as the cylinder wall except that it may not be of a lesser thickness than that required for a quarter size Charpy impact specimen. The weld must be made by the same procedures and subjected to the same heat treatment as the major weld on the cylinder. The specimen must be taken across the major seam and must be prepared in accordance with and must meet the requirements of CGA Pamphlet C-3. Should this specimen fail to meet the requirements, specimens may be taken from two additional cylinders or welded test plates from the same lot and tested. If either of the latter specimens fails to meet the requirements, the entire lot represented must be rejected.
(2) Guided bend test. A “root” bend test specimen must be cut from the cylinder or welded test plate, used for the tensile test specified in paragraph (l)(1) of this section and from any other seam or equivalent welded test plate if the seam is welded by a procedure different from that used for the major seam. Specimens must be taken across the particular seam being tested and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3.
(3) Alternate guided-bend test. This test may be used and must be as specified in CGA Pamphlet C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines a to b, is at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 100,000 psig, as provided in paragraph (c) of this section.
(4) Impact tests. One set of three impact test specimens (for each test) must be prepared and tested for determining the impact properties of the deposited weld metal—
(i) As part of the qualification of the welding procedure.
(ii) As part of the qualification of the operators.
(iii) For each “heat” of welding rodor wire used.
(iv) For each 1,000 feet of weld made with the same heat of welding rod or wire.
(v) All impact test specimens must be of the charpy type, keyhole or milled U-notch, and must conform in all respects to ASTM E 23 (IBR, see § 171.7 of this subchapter). Each set of impact specimens must be taken across the weld and have the notch located in the weld metal. When the cylinder material thickness is 2.5 mm or thicker, impact specimens must be cut from a cylinder or welded test plate used for the tensile or bend test specimens. The dimension along the axis of the notch must be reduced to the largest possible of 10 mm, 7.5 mm, 5 mm or 2.5 mm, depending upon cylinder thickness. When the material in the cylinder or welded test plate is not of sufficient thickness to prepare 2.5 mm impact test specimens, 2.5 mm specimens must be prepared from a welded test plate made from 1/8 inch thick material meeting the requirements specified in paragraph (o)(1), table 1, of this section and having a carbon analysis of .05 minimum, but not necessarily from one of the heats used in the lot of cylinders. The test piece must be welded by the same welding procedure as used on the particular cylinder seam being qualified and must be subjected to the same heat treatment.
(vi) Impact test specimens must be cooled to the design service temperature. The apparatus for testing the specimens must conform to requirements of ASTM Standard E 23. The test piece, as well as the handling tongs, must be cooled for a length of time sufficient to reach the service temperature. The temperature of the cooling device must be maintained within a range of plus or minus 3 °F. The specimen must be quickly transferred from the cooling device to the anvil of the testing machine and broken within a time lapse of not more than six seconds.
(vii) The impact properties of each set of impact specimens may not be less than the values in the following table:
(viii) When the average value of the three specimens equals or exceeds the minimum value permitted for a single specimen and the value for more than one specimen is below the required average value, or when the value for one specimen is below the minimum value permitted for a single specimen, a retest of three additional specimens must be made. The value of each of these retest specimens must equal or exceed the required average value. When an erratic result is caused by a defective specimen, or there is uncertainty in test procedure, a retest is authorized.
(m) Radiographic examination. Cylinders must be subject to a radiographic examination as follows:
(1) The techniques and acceptability of radiographic inspection must conform to the standards set forth in CGA Pamphlet C-3.
(2) One finished longitudinal seam must be selected at random from each lot of 100 or less successively produced and be radiographed throughout its entire length. Should the radiographic examination fail to meet the requirements of paragraph (m)(1) of this section, two additional seams of the same lot must be examined, and if either of these fail to meet the requirements of (m)(1) of this section, only those passing are acceptable.
(n) Rejected cylinders. Reheat treatment of rejected cylinders is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Welds may be repaired by suitable methods of fusion welding.
(o) Authorized materials of construction. Authorized materials of construction are as follows:
(1) Inner containment vessel (cylinder). Electric furnace steel of uniform quality must be used. Chemical analysis must conform to ASTM A 240/A 240M (IBR, see § 171.7 of this subchapter), Type 304 stainless steel. Chemical analysis must conform to ASTM A240, Type 304 Stainless Steel. A heat of steel made under table 1 and table 2 in this paragraph (o)(1) is acceptable, even though its check chemical analysis is slightly out of the specified range, if it is satisfactory in all other respects, provided the tolerances shown in table 3 in this paragraph (o)(1) are not exceeded. The following chemical analyses and physical properties are authorized:
Table 1—Authorized Materials
1 The carbon analysis must be reported to the nearest hundredth of one percent.
Table 2—Physical Properties
Table 3—Check Analysis Tolerances
1 Rephosphorized steels not subject to check analysis for phosphorus.
(2) Outer jacket. (i) Nonflammable cryogenic liquids. Cylinders intended for use in the transportation of nonflammable cryogenic liquid must have an outer jacket made of steel or aluminum.
(ii) Flammable cryogenic liquids. Cylinders intended for use in the transportation of flammable cryogenic liquid must have an outer jacket made of steel.
(p) Markings. (1) Markings must be stamped plainly and permanently on shoulder or top head of jacket or on a permanently attached plate or head protective ring.
(2) The letters “ST”, followed by the design service temperature (for example, ST-423F), must be marked on cylinders having a design service temperature of colder than minus 320 °F only. Location to be just below the DOT mark.
(3) The maximum weight of contents, in pounds (for example, “Max. Content 51 #”), must be marked on cylinders having a design service temperature colder than minus 320 °F only. Location to be near symbol.
(4) Special orientation instructions must be marked on the cylinder (for example, THIS END UP), if the cylinder is used in an orientation other than vertical with openings at the top of the cylinder.
(5) If the jacket of the cylinder is constructed of aluminum, the letters “AL” must be marked after the service pressure marking. Example: DOT-4L150 AL.
(6) Except for serial number and jacket material designation, each marking prescribed in this paragraph (p) must be duplicated on each cylinder by any suitable means.
(q) Inspector's report. In addition to the information required by § 178.35, the inspector's reports must contain information on:
(1) The jacket material and insulation type;
(2) The design service temperature
(3) The impact test results, on a lot basis.
§ 178.58   Specification 4DA welded steel cylinders for aircraft use.
(a) Type, size, and service pressure. A DOT 4DA is a welded steel sphere (two seamless hemispheres) or a circumferentially welded cylinder (two seamless drawn shells) with a water capacity not over 100 pounds and a service pressure of at least 500 but not over 900 psig.
(b) Steel. Open-hearth or electric steel of uniform quality must be used. A heat of steel made under table 1 in this paragraph (b), check chemical analysis of which is slightly out of the specified range, is acceptable, if satisfactory in all other respects, provided the tolerances shown in table 2 in this paragraph (b) are not exceeded except as approved by the Associate Administrator. The following chemical analyses are authorized:
Table 1—Authorized Materials
Table 2—Check Analysis Tolerances
1 Rephosphorized steels not subject to check analysis for phosphorus.
(c) Identification of material. Materials must be identified by any suitable method except that plates and billets for hot-drawn containers must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured in accordance with the following requirements:
(1) By best appliances and methods. No defect is acceptable that is likely to weaken the finished container appreciably. A reasonably smooth and uniform surface finish is required. No abrupt change in wall thickness is permitted. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(2) All seams of the sphere or cylinders must be fusion welded. Seams must be of the butt or joggle butt type and means must be provided for accomplishing complete penetration of the joint.
(e) Welding. Attachments to the container are authorized by fusion welding provided that such attachments are made of weldable steel, the carbon content of which may not exceed 0.25 percent except in the case of 4130 steel.
(f) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified test pressure may not exceed 67 percent of the minimum tensile strength of the steel as determined from the physical and burst tests required and may not be over 70,000 p.s.i. For any diameter container, the minimum wall thickness is 0.040 inch. Calculations must be made by the formulas in (f)(1) or (f)(2) of this section:
(1) Calculation for a sphere must be made by the following formula:
(2) Calculation for a cylinder must be made by the following formula:
(g) Heat treatment. The completed containers must be uniformly and properly heat-treated prior to tests. Heat-treatment of containers of the authorized analysis must be as follows:
(1) All containers must be quenched by oil, or other suitable medium except as provided in paragraph (g)(4) of this section.
(2) The steel temperature on quenching must be that recommended for the steel analysis, but may not exceed 1,750 °F.
(3) The steel must be tempered at the temperature most suitable for the analysis except that in no case shall the tempering temperature be less than 1,000 °F.
(4) The steel may be normalized at a temperature of 1,650 °F instead of being quenched, and containers so normalized need not be tempered.
(5) All cylinders, if water quenched or quenched with a liquid producing a cooling rate in excess of 80 percent of the cooling rate of water, must be inspected by the magnetic particle or dye penetrant method to detect the presence of quenching cracks. Any cylinder found to have a quench crack must be rejected and may not be requalified.
(h) Openings in container. Openings in the container must comply with the following requirements:
(1) Each opening in the container must be provided with a fitting, boss, or pad of weldable steel securely attached to the container by fusion welding.
(2) Attachments to a fitting, boss, or pad must be adequate to prevent leakage. Threads must comply with the following:
(i) Threads must be clean cut, even, without checks, and tapped to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, to have tight fit and calculated shear strength at least 10 times the test pressure of the container; gaskets required, adequate to prevent leakage.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) The test must be by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(2) Each cylinder must be tested to a minimum of two (2) times service pressure.
(3) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(4) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(j) Burst test. One container taken at random out of 200 or less must be hydrostatically tested to destruction. The rupture pressure must be included as part of the inspector's report.
(k) Flattening test. Spheres and cylinders must be subjected to a flattening test as follows:
(1) Flattening test for spheres. One sphere taken at random out of each lot of 200 or less must be subjected to a flattening test as follows:
(i) The test must be performed after the hydrostatic test.
(ii) The test must be at the weld between the parallel steel plates on a press with a welded seam, at right angles to the plates. Any projecting appurtenances may be cut off (by mechanical means only) prior to crushing.
(2) Flattening test for cylinders. One cylinder taken at random out of each lot of 200 or less, must be subjected to a flattening test as follows:
(i) The test must be performed after the hydrostatic test.
(ii) The test cylinder must be placed between wedge-shaped knife edges having a 60° angle, rounded to a 1/2 -inch radius.
(l) Radiographic inspection. Radiographic examinations is required on all welded joints which are subjected to internal pressure, except that at the discretion of the disinterested inspector, openings less than 25 percent of the sphere diameter need not be subjected to radiographic inspection. Evidence of any defects likely to seriously weaken the container must be cause for rejection.
(m) Physical test and specimens for spheres and cylinders. Spheres and cylinders must be subjected to a physical test as follows:
(1) A physical test for a sphere is required on 2 specimens cut from a flat representative sample plate of the same heat taken at random from the steel used to produce the sphere. This flat steel from which the 2 specimens are to be cut must receive the same heat-treatment as the spheres themselves. Sample plates to be taken for each lot of 200 or less spheres.
(2) Specimens for spheres have a gauge length of 2 inches with a width not over 1 1/2 inches, or a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when wall of sphere is not over 3/16 inch thick.
(3) A physical test for cylinders is required on 2 specimens cut from 1 cylinder taken at random out of each lot of 200 or less.
(4) Specimens for cylinder must conform to the following:
(i) A gauge length of 8 inches with a width not over 1 1/2 inches, a gauge length of 2 inches with a width not over 1 1/2 inches, a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3/16 inch thick.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) Heating of a specimen for any purpose is not authorized.
(5) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 percent offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
(n) Acceptable results for physical, flattening, and burst tests. The following are acceptable results of the physical, flattening and burst test:
(1) Elongation must be at least 20 percent for a 2-inch gauge length or 10 percent in other cases.
(2) Flattening is required to 50 percent of the original outside diameter without cracking.
(3) Burst pressure must be at least 3 times service pressure.
(o) Rejected containers. Reheat-treatment of rejected cylinders is authorized. Subsequent thereto, containers must pass all prescribed tests to be acceptable. Repair of welded seams by welding prior to reheat-treatment is authorized.
(p) Marking. Markings on each container must be stamped plainly and permanently on a permanent attachment or on a metal nameplate permanently secured to the container by means other than soft solder.
§ 178.59   Specification 8 steel cylinders with porous fillings for acetylene.
(a) Type and service pressure. A DOT 8 cylinder is a seamless cylinder with a service pressure of 250 psig. The following steel is authorized:
(1) A longitudinal seam if forge lap welded;
(2) Attachment of heads by welding or by brazing by dipping process; or
(3) A welded circumferential body seam if the cylinder has no longitudinal seam.
(b) Steel. Open-hearth, electric or basic oxygen process steel of uniform quality must be used. Content percent may not exceed the following: Carbon, 0.25; phosphorus, 0.045; sulphur, 0.050.
(c) Identification of steel. Materials must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is acceptable that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(e) Exposed bottom welds. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings.
(f) Heat treatment. Body and heads formed by drawing or pressing must be uniformly and properly heat treated prior to tests.
(g) Openings. Openings in the cylinders must comply with the following:
(1) Standard taper pipe threads are required;
(2) Length may not be less than as specified for American Standard pipe threads; tapped to gauge; clean cut, even, and without checks.
(h) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing. (i) At least one (1) cylinder selected at random out of each lot of 200 or fewer must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of 750 psig.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(v) If the selected cylinder passes the volumetric expansion test, each remaining cylinder in the lot must be pressure tested in accordance with paragraph (h)(2) of this section. If the selected cylinder fails, each cylinder in the lot must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 at 750 psig. Each cylinder with a permanent expansion that does not exceed 10% is acceptable.
(2) Pressure testing. (i) If the selected cylinder passes the water-jacket or direct expansion test, the remaining cylinders in each lot must be pressure tested by the proof pressure, water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested between 500 and 600 psig and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 section 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(i) Leakage test. Cylinders with bottoms closed in by spinning must be subjected to a leakage test by setting the interior air or gas pressure to not less than the service pressure. Cylinders which leak must be rejected.
(j) Physical test. A physical test must be conducted as follows:
(1) The test is required on 2 specimens cut longitudinally from 1 cylinder or part thereof taken at random out of each lot of 200 or less, after heat treatment.
(2) Specimens must conform to a gauge length of 8 inches with a width not over 1 1/2 inches, a gauge length of 2 inches with width not over 1 1/2 , or a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3/16 inch thick.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi and the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
(4) Yield strength may not exceed 73 percent of tensile strength. Elongation must be at least 40 percent in 2 inch or 20 percent in other cases.
(k) Rejected cylinders. Reheat treatment of rejected cylinder is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding is authorized.
(l) Porous filling. (1) Cylinders must be filled with a porous material in accordance with the following:
(i) The porous material may not disintegrate or sag when wet with solvent or when subjected to normal service;
(ii) The porous filling material must be uniform in quality and free of voids, except that a well drilled into the filling material beneath the valve is authorized if the well is filled with a material of such type that the functions of the filling material are not impaired;
(iii) Overall shrinkage of the filling material is authorized if the total clearance between the cylinder shell and filling material, after solvent has been added, does not exceed 1/2 of 1 percent of the respective diameter or length, but not to exceed 1/8 inch, measured diametrically and longitudinally;
(iv) The clearance may not impair the functions of the filling material;
(v) The installed filling material must meet the requirements of CGA C-12 (IBR, see § 171.7 of this subchapter); and
(vi) Porosity of filling material may not exceed 80 percent except that filling material with a porosity of up to 92 percent may be used when tested with satisfactory results in accordance with CGA Pamphlet C-12.
(2) When the porosity of each cylinder is not known, a cylinder taken at random from a lot of 200 or less must be tested for porosity. If the test cylinder fails, each cylinder in the lot may be tested individually and those cylinders that pass the test are acceptable.
(3) For filling that is molded and dried before insertion in cylinders, porosity test may be made on a sample block taken at random from material to be used.
(4) The porosity of the filling material must be determined. The amount of solvent at 70 °F for a cylinder:
(i) Having shell volumetric capacity above 20 pounds water capacity (nominal) may not exceed the following:
(ii) Having volumetric capacity of 20 pounds or less water capacity (nominal), may not exceed the following:
(m) Tare weight. The tare weight is the combined weight of the cylinder proper, porous filling, valve, and solvent, without removable cap.
(n) Duties of inspector. In addition to the requirements of § 178.35, the inspector is required to—
(1) Certify chemical analyses of steel used, signed by manufacturer thereof; also verify by, check analyses of samples taken from each heat or from 1 out of each lot of 200 or less, plates, shells, or tubes used.
(2) Verify compliance of cylinder shells with all shell requirements; inspect inside before closing in both ends; verify heat treatment as proper; obtain all samples for all tests and for check analyses; witness all tests; verify threads by gauge; report volumetric capacity and minimum thickness of wall noted.
(3) Prepare report on manufacture of steel shells in form prescribed in § 178.35. Furnish one copy to manufacturer and three copies to the company that is to complete the cylinders.
(4) Determine porosity of filling and tare weights; verify compliance of marking with prescribed requirements; obtain necessary copies of steel shell reports; and furnish complete reports required by this specification to the person who has completed the manufacture of the cylinders and, upon request, to the purchaser. The test reports must be retained by the inspector for fifteen years from the original test date of the cylinder.
(o) Marking. (1) Marking on each cylinder must be stamped plainly and permanently on or near the shoulder, top head, neck or valve protection collar which is permanently attached to the cylinder and forming integral part thereof.
(2) Tare weight of cylinder, in pounds and ounces, must be marked on the cylinder.
(3) Cylinders, not completed, when delivered must each be marked for identification of each lot of 200 or less.
§ 178.60   Specification 8AL steel cylinders with porous fillings for acetylene.
(a) Type and service pressure. A DOT 8AL cylinder is a seamless steel cylinder with a service pressure of 250 psig. However, the attachment of heads by welding or by brazing by dipping process and a welded circumferential body seam is authorized. Longitudinal seams are not authorized.
(b) Authorized steel. The authorized steel is as specified in table I of appendix A to this part.
(c) Identification of steel. Material must be identified by any suitable method except that plates and billets for hot-drawn cylinders must be marked with heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(e) Footrings. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings.
(f) Welding or brazing. Welding or brazing for any purpose whatsoever is prohibited except as follows:
(1) The attachment to the tops or bottoms of cylinders of neckrings, footrings, handlers, bosses, pads, and valve protecting rings is authorized provided that such attachments and the portion of the container to which they are attached are made of weldable steel, the carbon content of which may not exceed 0.25 percent.
(2) Heat treatment is not required after welding or brazing weldable low carbon parts to attachments, specified in paragraph (f)(1) of this section, of similar material which have been previously welded or brazed to the top or bottom of cylinders and properly heat treated, provided such subsequent welding or brazing does not produce a temperature in excess of 400 °F in any part of the top or bottom material.
(g) Wall thickness; wall stress. The wall thickness/wall stress of the cylinder must conform to the following:
(1) The calculated wall stress at 750 psi may not exceed 35,000 psi, or one-half of the minimum ultimate strength of the steel as determined in paragraph (l) of this section, whichever value is the smaller. The measured wall thickness may not include galvanizing or other protective coating.
(i) Calculation of wall stress must be made by the formula:
(ii) Either D or d must be calculated from the relation D = d + 2t, where t = minimum wall thickness.
(2) Cylinders with a wall thickness less than 0.100 inch, the ratio of straight side wall length to outside diameter may not exceed 3.5.
(3) For cylinders having outside diameter over 5 inches, the minimum wall thickness must be 0.087 inch.
(h) Heat treatment. Each cylinder must be uniformly and properly heat treated, prior to tests, by any suitable method in excess of 1100 °F. Heat treatment must be accomplished after all forming and welding operations, except that when brazed joints are used, heat treatment must follow any forming and welding operations but may be done before, during, or after the brazing operations. Liquid quenching is not authorized.
(i) Openings. Standard taper pipe threads required in all openings. The length of the opening may not be less than as specified for American Standard pipe threads; tapped to gauge; clean cut, even, and without checks.
(j) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing. (i) At least one (1) cylinder selected at random out of each lot of 200 or less must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR; see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) The selected cylinder must be tested to a minimum of 750 psig.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(v) If the selected cylinder passes the volumetric expansion test, each remaining cylinder in the lot must be pressure tested in accordance with paragraph (h)(2) of this section. If the selected cylinder fails, each cylinder in the lot must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 at 750 psig. Each cylinder with a permanent expansion that does not exceed 10% is acceptable.
(2) Pressure testing. (i) If the selected cylinder passes the water-jacket or direct expansion test, the remaining cylinders in each lot must be pressure tested by the proof pressure water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested between 500 and 600 psig and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 section 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(k) Leakage test. Cylinders with bottoms closed in by spinning must be leakage tested by setting the interior air or gas pressure at not less than the service pressure. Any cylinder that leaks must be rejected.
(l) Physical test. A physical test must be conducted as follows;
(1) The test is required on 2 specimens cut longitudinally from 1 cylinder or part thereof taken at random out of each lot of 200 or less, after heat treatment.
(2) Specimens must conform to a gauge length of 8 inches with a width not over 1 1/2 inches, a gauge length 2 inches with a width not over 1 1/2 inches, or a gauge length at least 24 times thickness with a width not over 6 times thickness is authorized when a cylinder wall is not over 3/16 inch thick.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “offset” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”) corresponding to the stress at which the 0.2 percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2 offset.
(iii) For the purpose of strain measurement, the initial strain must be set while the specimen is under a stress of 12,000 psi, the strain indicator reading being set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
(m) Elongation. Physical test specimens must show at least a 40 percent elongation for a 2 inch gauge length or at least a 20 percent elongation in other cases. Except that these elongation percentages may be reduced numerically by 2 for 2 inch specimens and 1 in other cases for each 7,500 psi increment of tensile strength above 50,000 psi to a maximum of four such increments.
(n) Weld tests. Specimens taken across the circumferentially welded seam must be cut from one cylinder taken at random from each lot of 200 or less cylinders after heat treatment and must pass satisfactorily the following tests:
(1) Tensile test. A specimen must be cut from one cylinder of each lot of 200 or less, or welded test plate. The specimen must be taken from across the major seam and must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3. Should this specimen fail to meet the requirements, specimens may be taken from two additional cylinders or welded test plates from the same lot and tested. If either of the latter specimens fail to meet the requirements, the entire lot represented must be rejected.
(2) Guided bend test. A root bend test specimen must be cut from the cylinder or welded test plate, used for the tensile test specified in paragraph (n)(1) of this section. Specimens must be prepared and tested in accordance with and must meet the requirements of CGA Pamphlet C-3.
(3) Alternate guided-bend test. This test may be used and must be as required by CGA Pamphlet C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gage lines-a to b, must be at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 psi, as provided in paragraph (m) of this section.
(o) Rejected cylinders. Reheat treatment of rejected cylinders is authorized. Subsequent thereto, cylinders must pass all prescribed tests to be acceptable. Repair by welding is authorized.
(p) Porous filling. (1) Cylinders must be filled with a porous material in accordance with the following:
(i) The porous material may not disintegrate or sag when wet with solvent or when subjected to normal service;
(ii) The filling material must be uniform in quality and free of voids, except that a well drilled into the filling material beneath the valve is authorized if the well is filled with a material of such type that the functions of the filling material are not impaired;
(iii) Overall shrinkage of the filling material is authorized if the total clearance between the cylinder shell and filling material, after solvent has been added, does not exceed 1/2 of 1 percent of the respective diameter or length but not to exceed 1/8 inch, measured diametrically and longitudinally;
(iv) The clearance may not impair the functions of the filling material;
(v) The installed filling material must meet the requirements of CGA C-12 (IBR, see § 171.7 of this subchapter); and
(vi) Porosity of filling material may not exceed 80 percent except that filling material with a porosity of up to 92 percent may be used when tested with satisfactory results in accordance with CGA Pamphlet C-12.
(2) When the porosity of each cylinder is not known, a cylinder taken at random from a lot of 200 or less must be tested for porosity. If the test cylinder fails, each cylinder in the lot may be tested individually and those cylinders that pass the test are acceptable.
(3) For filling that is molded and dried before insertion in cylinders, porosity test may be made on sample block taken at random from material to be used.
(4) The porosity of the filling material must be determined; the amount of solvent at 70 °F for a cylinder:
(i) Having shell volumetric capacity above 20 pounds water capacity (nominal) may not exceed the following:
(ii) Having volumetric capacity of 20 pounds or less water capacity (nominal), may not exceed the following:
(q) Tare weight. The tare weight is the combined weight of the cylinder proper, porous filling, valve, and solvent, but without removable cap.
(r) Duties of inspector. In addition to the requirements of § 178.35, the inspector shall—
(1) Certify chemical analyses of steel used, signed by manufacturer thereof; also verify by check analyses, of samples taken from each heat or from 1 out of each lot of 200 or less plates, shells, or tubes used.
(2) Verify compliance of cylinder shells with all shell requirements, inspect inside before closing in both ends, verify heat treatment as proper; obtain all samples for all tests and for check analyses, witness all tests; verify threads by gauge, report volumetric capacity and minimum thickness of wall noted.
(3) Report percentage of each specified alloying element in the steel. Prepare report on manufacture of steel shells in form prescribed in § 178.35. Furnish one copy to manufacturer and three copies to the company that is to complete the cylinders.
(4) Determine porosity of filling and tare weights; verify compliance of marking with prescribed requirements; obtain necessary copies of steel shell reports prescribed in paragraph (b) of this section; and furnish complete test reports required by this specification to the person who has completed the manufacturer of the cylinders and, upon request, to the purchaser. The test reports must be retained by the inspector for fifteen years from the original test date of the cylinder.
(s) Marking. (1) Tare weight of cylinder, in pounds and ounces, must be marked on the cylinder.
(2) Cylinders, not completed, when delivered must each be marked for identification of each lot of 200 or less.
(3) Markings must be stamped plainly and permanently in locations in accordance with the following:
(i) On shoulders and top heads not less than 0.087 inch thick; or
(ii) On neck, valve boss, valve protection sleeve, or similar part permanently attached to the top end of cylinder; or
(iii) On a plate of ferrous material attached to the top of the cylinder or permanent part thereof; the plate must be at least 1/16 inch thick, and must be attached by welding, or by brazing at a temperature of at least 1,100 °F throughout all edges of the plate. Sufficient space must be left on the plate to provide for stamping at least four (4) retest dates.
§ 178.61   Specification 4BW welded steel cylinders with electric-arc welded seam.
(a) Type, size, pressure, and application. A DOT 4BW cylinder has a spherical or cylindrical design, a water capacity of 1,000 pounds or less, and a service pressure range of 225 to 500 psig. Closures made by the spinning process are not authorized.
(1) Spherical designs are permitted to have only one circumferentially electric-arc welded seam.
(2) Cylindrical designs must be of circumferentially welded electric-arc construction; longitudinally electric-arc welded seams are permitted.
(b) Steel. (1) The steel used in the construction of the cylinder must be as specified in table 1 of appendix A to this part. The cylinder manufacturer must maintain a record of intentionally added alloying elements.
(2) Material for heads must meet the requirements of paragraph (b)(1) of this section or be open hearth, electric or basic oxygen carbon steel of uniform quality. Content percent may not exceed the following: Carbon 0.25, Manganese 0.60, Phosphorus 0.045, Sulfur 0.050. Heads must be hemispherical or ellipsoidal in shape with a maximum ratio of 2:1. If low carbon steel is used, the thickness of such heads must be determined by using a maximum wall stress of 24,000 psi in the formula described in paragraph (f)(2) of this section.
(c) Identification of material. Pressure-retaining materials must be identified by any suitable method that does not compromise the integrity of the cylinder. Plates and billets for hotdrawn cylinders must be marked with the heat number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart and the following:
(1) No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface is required. Exposed bottom welds on cylinders over 18 inches long must be protected by footrings. Minimum thickness of heads may not be less than 90 percent of the required thickness of the sidewall. Heads must be concave to pressure.
(2) Circumferential seams must be by electric-arc welding. Joints must be butt with one member offset (joggle butt) or with a lap joint. Joints must have a minimum overlap of at least four (4) times nominal sheet thickness.
(3) Longitudinal electric-arc welded seams (in shells) must be of the butt welded type. Welds must be made by a machine process including automatic feed and welding guidance mechanisms. Longitudinal seams must have complete joint penetration, and must be free from undercuts, overlaps or abrupt ridges or valleys. Misalignment of mating butt edges may not exceed 1/6 inch of nominal sheet thickness or 1/32 inch whichever is less. All joints with nominal sheet thickness up to and including 1/8 inch must be tightly butted. When nominal sheet thickness is greater than 1/8 inch, the joint must be gapped with maximum distance equal to one-half the nominal sheet thickness or 1/32 inch whichever is less. Joint design, preparation, and fit-up must be such that requirements of this paragraph (d) are satisfied.
(4) Welding procedures and operators must be qualified in accordance with CGA C-3 (IBR, see § 171.7 of this subchapter).
(5)(i) Welds of the cylinders must be subjected to radioscopic or radiographic examination as follows:
(ii) Radioscopy or radiography must be in conformance with CGA C-3 (IBR; see § 171.7 of this subchapter). Maximum joint efficiency will be 1.0 when each longitudinal seam is examined completely. Maximum joint efficiency will be 0.90 when one cylinder from each lot of 50 consecutively welded cylinders is spot examined. In addition, one out of the first five cylinders welded following a shutdown of welding operations exceeding four hours must be spot examined. Spot radiographs, when required, must be made of a finished welded cylinder and must include the circumferential weld for 2 inches in both directions from the intersection of the longitudinal and circumferential welds and include at least 6 inches of the longitudinal weld. Maximum joint efficiency of 0.75 will be permissible without radiography or radioscopy. When fluoroscopic examination is used, permanent film records need not be retained. Circumferential welds need not be examined, except as part of spot examination.
(e) Welding of attachments. The attachment to the tops and bottoms only of cylinders by welding of neckrings, footrings, handles, bosses, pads and valve protection rings is authorized provided that such attachments and the portion of the container to which they are attached are made of weldable steel, the carbon content of which may not exceed 0.25 percent.
(f) Wall thickness. (1) For outside diameters over 6 inches the minimum wall thickness must be 0.078 inch. In any case, the minimum wall thickness must be such that the wall stress calculated by the formula listed in paragraph (f)(2) of this section may not exceed the lesser value of any of the following:
(i) The value referenced in paragraph (b) of this section for the particular material under consideration.
(ii) One-half of the minimum tensile strength of the material determined as required in paragraph (j) of this section.
(iii) 35,000 psig.
(2) Stress must be calculated by the following formula:
(3) For a cylinder with a wall thickness less than 0.100 inch, the ratio of tangential length to outside diameter may not exceed 4 to 1 (4:1).
(g) Heat treatment. Cylinders must be heat treated in accordance with the following requirements:
(1) Each cylinder must be uniformly and properly heat treated prior to test by the applicable method referenced in table 1 of appendix A to this part. Heat treatment must be accomplished after all forming and welding operations, except that when brazed joints are used, heat treatment must follow any forming and welding operations, but may be done before, during or after the brazing operations (see paragraph (n) of this section for weld repairs).
(2) Heat treatment is not required after welding of weldable low-carbon parts to attachments of similar material which have been previously welded to the top or bottom of cylinders and properly heat treated, provided such subsequent welding does not produce a temperature in excess of 400 °F in any part of the top or bottom material.
(h) Openings in cylinders. Openings in cylinders must comply with the following requirements:
(1) All openings must be in heads or bases.
(2) Each opening in a spherical-type cylinder must be provided with a fitting, boss, or pad of weldable steel securely attached to the cylinder by fusion welding.
(3) Each opening in a cylindrical-type cylinder must be provided with a fitting, boss, or pad securely attached to the cylinder by welding.
(4) If threads are used, they must comply with the following:
(i) Threads must be clean cut, even, without checks, and tapped to gauge.
(ii) Taper threads must be of length not less than as specified for American Standard Taper Pipe Threads.
(iii) Straight threads, having at least four (4) engaged threads, must have a tight fit and calculated shear strength at least ten (10) times the test pressure of the cylinder. Gaskets, adequate to prevent leakage, are required.
(iv) A brass fitting may be brazed to the steel boss or flange on cylinders used as component parts of handheld fire extinguishers.
(i) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Lot testing. (i) At least one (1) cylinder randomly selected out of each lot of 200 or fewer must be tested by the water-jacket or direct expansion method as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each selected cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iv) Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.
(2) Pressure testing. (i) The remaining cylinders in each lot must be pressure tested by the proof pressure, water-jacket or direct expansion test method as prescribed in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(3) Burst testing. One finished cylinder selected at random out of each lot of 500 or less successively produced must be hydrostatically tested to four (4) times service pressure without bursting. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(j) Mechanical tests. Mechanical tests must be conducted to determine yield strength, tensile strength, elongation as a percentage, and reduction of area of material as a percentage, as follows:
(1) Specimens must be taken from one cylinder after heat treatment as illustrated in appendix A to this subpart, chosen at random from each lot of 200 or fewer, as follows:
(i) One specimen must be taken longitudinally from the body section at least 90 degrees away from the weld.
(ii) One specimen must be taken from either head on a cylinder when both heads are made of the same material. However, if the two heads are made of differing materials, a specimen must be taken from each head.
(iii) If due to welded attachments on the top head there is insufficient surface from which to take a specimen, it may be taken from a representative head of the same heat treatment as the test cylinder.
(2) Specimens must conform to the following:
(i) When a cylinder wall is 3/16 inch thick or less, one the following gauge lengths is authorized: A gauge length of 8 inches with a width not over

1 1/2 inches, a gauge length of 2 inches with a width not over 1 1/2 inches, or a gauge length at least twenty-four (24) times the thickness with a width not over six (6) times the thickness.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) When size of the cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows. When specimens are taken, and prepared in this manner, the inspector's report must show, in connection with the record of physical tests, detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by either the “off-set” method or the “extension under load” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) In using the “extension under load” method, the total strain (or “extension under load”), corresponding to the stress at which the 0.2-percent permanent strain occurs may be determined with sufficient accuracy by calculating the elastic extension of the gauge length under appropriate load and adding thereto 0.2 percent of the gauge length. Elastic extension calculations must be based on an elastic modulus of 30,000,000. In the event of controversy, the entire stress-strain diagram must be plotted and the yield strength determined from the 0.2-percent offset.
(iii) For strain measurement, the initial strain reference must be set while the specimen is under a stress of 12,000 psig, and the strain indicator reading must be set at the calculated corresponding strain.
(iv) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
(k) Elongation. Mechanical test specimens must show at least a 40 percent elongation for a 2-inch gauge length or at least 20 percent in other cases. However, elongation percentages may be reduced numerically by 2 percent for 2-inch specimens, and by 1 percent in other cases, for each 7,500 psi increase of tensile strength above 50,000 psig. The tensile strength may be incrementally increased by four increments of 7,500 psig for a maximum total of 30,000 psig.
(l) Tests of welds. Welds must be subjected to the following tests:
(1) Tensile test. A specimen must be removed from one cylinder of each lot of 200 or fewer. The specimen must be taken from across the longitudinal seam and must be prepared and tested in conformance with the requirements of CGA C-3 (IBR, see § 171.7 of this subchapter).
(2) Guided bend test. A root bend test specimen must be removed from the cylinder or welded test plate used for the tensile test specified in paragraph (m)(1) of this section. Specimens must be taken from across the longitudinal seam and must be prepared and tested in conformance with the requirements of CGA C-3. If the specimen fails to meet the requirements, one specimen each must be taken from two additional cylinders or welded test plates from the same lot as the previously tested cylinder or added test plate and tested. If either of these latter two specimens fails to meet the requirements, the entire lot represented must be rejected.
(3) Alternate guided bend test. This test may be used and must be as required by CGA C-3. The specimen must be bent until the elongation at the outer surface, adjacent to the root of the weld, between the lightly scribed gauge lines a to b, must be at least 20 percent, except that this percentage may be reduced for steels having a tensile strength in excess of 50,000 psig, as provided in paragraph (k) of this section. Should this specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested as the previously tested cylinder or added test plate. If either of these latter two specimens fails to meet the requirements, the entire lot represented must be rejected.
(m) Rejected cylinders. (1) Unless otherwise stated, if a sample cylinder or specimen taken from a lot of cylinders fails the prescribed test, then two additional specimens must be selected from the same lot and subjected to the prescribed test. If either of these fails the test, then the entire lot must be rejected.
(2) Reheat treatment of rejected cylinders. Reheat treatment is authorized for a rejected cylinder in accordance with this paragraph (m)(2). After reheat treatment, a cylinder must pass all prescribed tests in this section to be considered acceptable. Repair of welded seams by welding is authorized. For cylinders less than or equal to an outside diameter of 6 inches, welded seam repairs greater than 1 inch in length shall require reheat treatment of the cylinder. For cylinders greater than an outside diameter of 6 inches, welded seam repairs greater than 3 inches in length shall require reheat treatment.
(n) Markings. (1) Markings must be as required in § 178.35 and in addition must be stamped plainly and permanently in one of the following locations on the cylinder:
(i) On shoulders and top heads whose wall thickness is not less than 0.087 inch thick.
(ii) On side wall adjacent to top head for side walls not less than 0.090 inch thick.
(iii) On a cylindrical portion of the shell that extends beyond the recessed bottom of the cylinder constituting an integral and non-pressure part of the cylinder.
(iv) On a plate attached to the top of the cylinder or permanent part thereof; sufficient space must be left on the plate to provide for stamping at least six retest dates; the plate must be at least 1/16 -inch thick and must be attached by welding at a temperature of 1,100 °F, throughout all edges of the plate.
(v) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder.
(vi) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 30 pounds.
(2) Embossing the cylinder head or side wall is not permitted.
(o) Inspector's report. In addition to the information required by § 178.35, the inspector's report must indicate the type and amount of radiography.
§ 178.65   Specification 39 non-reusable (non-refillable) cylinders.
(a) Type, size, service pressure, and test pressure. A DOT 39 cylinder is a seamless, welded, or brazed cylinder with a service pressure not to exceed 80 percent of the test pressure. Spherical pressure vessels are authorized and covered by references to cylinders in this specification.
(1) Size limitation. Maximum water capacity may not exceed: (i) 55 pounds (1,526 cubic inches) for a service pressure of 500 p.s.i.g. or less, and (ii) 10 pounds (277 cubic inches) for a service pressure in excess of 500 p.s.i.g.
(2) Test pressure. The minimum test pressure is the maximum pressure of contents at 130 °F or 180 p.s.i.g. whichever is greater.
(3) Pressure of contents. The term “pressure of contents” as used in this specification means the total pressure of all the materials to be shipped in the cylinder.
(b) Material; steel or aluminum. The cylinder must be constructed of either steel or aluminum conforming to the following requirements:
(1) Steel. (i) The steel analysis must conform to the following:
(ii) For a cylinder made of seamless steel tubing with integrally formed ends, hot drawn, and finished, content percent for the following may not exceed: Carbon, 0.55; phosphorous, 0.045; sulfur, 0.050.
(iii) For non-heat treated welded steel cylinders, adequately killed deep drawing quality steel is required.
(iv) Longitudinal or helical welded cylinders are not authorized for service pressures in excess of 500 p.s.i.g.
(2) Aluminum. Aluminum is not authorized for service pressures in excess of 500 psig. The analysis of the aluminum must conform to the Aluminum Association standard for alloys 1060, 1100, 1170, 3003, 5052, 5086, 5154, 6061, and 6063, as specified in its publication entitled “Aluminum Standards and Data” (IBR, see § 171.7 of this subchapter).
(3) Material with seams, cracks, laminations, or other injurious defects not permitted.
(4) Material used must be identified by any suitable method.
(c) Manufacture. (1) General manufacturing requirements are as follows:
(i) The surface finish must be uniform and reasonably smooth.
(ii) Inside surfaces must be clean, dry, and free of loose particles.
(iii) No defect of any kind is permitted if it is likely to weaken a finished cylinder.
(2) Requirements for seams:
(i) Brazing is not authorized on aluminum cylinders.
(ii) Brazing material must have a melting point of not lower than 1,000 °F.
(iii) Brazed seams must be assembled with proper fit to ensure complete penetration of the brazing material throughout the brazed joint.
(iv) Minimum width of brazed joints must be at least four times the thickness of the shell wall.
(v) Brazed seams must have design strength equal to or greater than 1.5 times the minimum strength of the shell wall.
(vi) Welded seams must be properly aligned and welded by a method that provides clean, uniform joints with adequate penetration.
(vii) Welded joints must have a strength equal to or greater than the minimum strength of the shell material in the finished cylinder.
(3) Attachments to the cylinder are permitted by any means which will not be detrimental to the integrity of the cylinder. Welding or brazing of attachments to the cylinder must be completed prior to all pressure tests.
(4) Welding procedures and operators must be qualified in accordance with CGA Pamphlet C-3 (IBR, see § 171.7 of this subchapter).
(d) Wall thickness. The minimum wall thickness must be such that the wall stress at test pressure does not exceed the yield strength of the material of the finished cylinder wall. Calculations must be made by the following formulas:
(1) Calculation of the stress for cylinders must be made by the following formula:
(2) Calculation of the stress for spheres must be made by the following formula:
(e) Openings and attachments. Openings and attachments must conform to the following:
(1) Openings and attachments are permitted on heads only.
(2) All openings and their reinforcements must be within an imaginary circle, concentric to the axis of the cylinder. The diameter of the circle may not exceed 80 percent of the outside diameter of the cylinder. The plane of the circle must be parallel to the plane of a circumferential weld and normal to the long axis of the cylinder.
(3) Unless a head has adequate thickness, each opening must be reinforced by a securely attached fitting, boss, pad, collar, or other suitable means.
(4) Material used for welded openings and attachments must be of weldable quality and compatible with the material of the cylinder.
(f) Pressure testing. (1) Each cylinder must be proof pressure tested as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) The leakage test must be conducted by submersion under water or by some other method that will be equally sensitive.
(ii) If the cylinder leaks, evidences visible distortion or evidences any other defect while under test, it must be rejected (see paragraph (h) of this section).
(iii) If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA, C-1 section 7.1.2.
(2) One cylinder taken from the beginning of each lot, and one from each 1,000 or less successively produced within the lot thereafter, must be hydrostatically tested to destruction. The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. The entire lot must be rejected (see paragraph (h) of this section) if:
(i) A failure occurs at a gage pressure less than 2.0 times the test pressure;
(ii) A failure initiates in a braze or a weld or the heat affected zone thereof;
(iii) A failure is other than in the sidewall of a cylinder longitudinal with its long axis; or
(iv) In a sphere, a failure occurs in any opening, reinforcement, or at a point of attachment.
(3) A “lot” is defined as the quantity of cylinders successively produced per production shift (not exceeding 10 hours) having identical size, design, construction, material, heat treatment, finish, and quality.
(g) Flattening test. One cylinder must be taken from the beginning of production of each lot (as defined in paragraph (f)(3) of this section) and subjected to a flattening test as follows:
(1) The flattening test must be made on a cylinder that has been tested at test pressure.
(2) A ring taken from a cylinder may be flattened as an alternative to a test on a complete cylinder. The test ring may not include the heat affected zone or any weld. However, for a sphere, the test ring may include the circumferential weld if it is located at a 45 degree angle to the ring, ±5 degrees.
(3) The flattening must be between 60 degrees included-angle, wedge shaped knife edges, rounded to a 0.5 inch radius.
(4) Cylinders and test rings may not crack when flattened so that their outer surfaces are not more than six times wall thickness apart when made of steel or not more than ten times wall thickness apart when made of aluminum.
(5) If any cylinder or ring cracks when subjected to the specified flattening test, the lot of cylinders represented by the test must be rejected (see paragraph (h) of this section).
(h) Rejected cylinders. Rejected cylinders must conform to the following requirements:
(1) If the cause for rejection of a lot is determinable, and if by test or inspection defective cylinders are eliminated from the lot, the remaining cylinders must be qualified as a new lot under paragraphs (f) and (g) of this section.
(2) Repairs to welds are permitted. Following repair, a cylinder must pass the pressure test specified in paragraph (f) of this section.
(3) If a cylinder made from seamless steel tubing fails the flattening test described in paragraph (g) of this section, suitable uniform heat treatment must be used on each cylinder in the lot. All prescribed tests must be performed subsequent to this heat treatment.
(i) Markings. (1) The markings required by this section must be durable and waterproof. The requirements of § 178.35(h) do not apply to this section.
(2) Required markings are as follows:
(i) DOT-39.
(ii) NRC.
(iii) The service pressure.
(iv) The test pressure.
(v) The registration number (M****) of the manufacturer.
(vi) The lot number.
(vii) The date of manufacture if the lot number does not establish the date of manufacture.
(viii) With one of the following statements:
(A) For cylinders manufactured prior to October 1, 1996: “Federal law forbids transportation if refilled-penalty up to $25,000 fine and 5 years imprisonment (49 U.S.C. 1809)” or “Federal law forbids transportation if refilled-penalty up to $500,000 fine and 5 years imprisonment (49 U.S.C. 5124).”
(B) For cylinders manufactured on or after October 1, 1996: “Federal law forbids transportation if refilled-penalty up to $500,000 fine and 5 years imprisonment (49 U.S.C. 5124).”
(3) The markings required by paragraphs (i)(2)(i) through (i)(2)(v) of this section must be in numbers and letters at least 1/8 inch high and displayed sequentially. For example:
(4) No person may mark any cylinder with the specification identification “DOT-39” unless it was manufactured in compliance with the requirements of this section and its manufacturer has a registration number (M****) from the Associate Administrator.
§ 178.68   Specification 4E welded aluminum cylinders.
(a) Type, size and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity (nominal) of not over 1,000 pounds and a service pressure of at least 225 to not over 500 psig. The cylinder must be constructed of not more than two seamless drawn shells with no more than one circumferential weld. The circumferential weld may not be closer to the point of tangency of the cylindrical portion with the shoulder than 20 times the cylinder wall thickness. Cylinders or shells closed in by spinning process and cylinders with longitudinal seams are not authorized.
(b) Authorized material. (1) The cylinder must be constructed of aluminum of uniform quality. The following chemical analyses are authorized:
Table 1 to Paragraph ( b )(1)—Authorized Materials
(2) The aluminum used in the construction of the cylinder must be as specified in Table 1 to paragraph (b)(1) of this section. Analyses must regularly be made only for the elements specifically mentioned in the table. If, however, the presence of other elements is indicated in the course of routine analysis, further analysis should be made to determine conformance with the limits specified for other elements. The cylinder manufacturer must maintain a record of intentionally added alloying elements.
(c) Identification. Material must be identified by any suitable method that will identify the alloy and manufacturer's lot number.
(d) Manufacture. Cylinders must be manufactured using equipment and processes adequate to ensure that each cylinder produced conforms to the requirements of this subpart. No defect is permitted that is likely to weaken the finished cylinder appreciably. A reasonably smooth and uniform surface finish is required. All welding must be by the gas shielded arc process.
(e) Welding. The attachment to the tops and bottoms only of cylinders by welding of neckrings, flanges, footrings, handles, bosses, pads, and valve protection rings is authorized. However, such attachments and the portion of the cylinder to which it is attached must be made of weldable aluminum alloys.
(f) Wall thickness. The wall thickness of the cylinder must conform to the following:
(1) The minimum wall thickness of the cylinder must be 0.140 inch. In any case, the minimum wall thickness must be such that calculated wall stress at twice service pressure may not exceed the lesser value of either of the following:
(i) 20,000 psi.
(ii) One-half of the minimum tensile strength of the material as required in paragraph (j) of this section.
(2) Calculation must be made by the following formula:
(3) Minimum thickness of heads and bottoms may not be less than the minimum required thickness of the side wall.
(g) Opening in cylinder. Openings in cylinders must conform to the following:
(1) All openings must be in the heads or bases.
(2) Each opening in cylinders, except those for safety devices, must be provided with a fitting, boss, or pad, securely attached to cylinder by welding by inert gas shielded arc process or by threads. If threads are used, they must comply with the following:
(i) Threads must be clean-cut, even, without checks and cut to gauge.
(ii) Taper threads to be of length not less than as specified for American Standard taper pipe threads.
(iii) Straight threads, having at least 4 engaged threads, to have tight fit and calculated shear strength at least 10 times the test pressure of the cylinder; gaskets required, adequate to prevent leakage.
(3) Closure of a fitting, boss, or pad must be adequate to prevent leakage.
(h) Pressure testing. Each cylinder must successfully withstand a pressure test as follows:
(1) Pressure test. All cylinders with a wall stress greater than 18,000 psig must be tested by water-jacket or direct expansion method as prescribed in CGA C-1 (IBR, see § 171.7 of this subchapter). The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) Each cylinder must be tested to a minimum of two (2) times service pressure.
(ii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(iii) Permanent volumetric expansion may not exceed 12 percent of the total volumetric expansion at test pressure.
(2) Lot testing. (i) Cylinders with a wall stress of 18,000 psig or less may be lot tested. At least one (1) cylinder randomly selected out of each lot of 200 or less must be tested by the water-jacket or direct expansion method as prescribed in CGA C-1. The testing equipment must be calibrated as prescribed in CGA C-1. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1, section 5.7.2.
(ii) Each selected cylinder must be tested to a minimum of two (2) times service pressure.
(iii) The minimum test pressure must be maintained at least 30 seconds and sufficiently longer to ensure complete expansion. Any internal pressure applied after heat-treatment and prior to the official test may not exceed 90 percent of the test pressure.
(iv) Permanent volumetric expansion may not exceed 12 percent of the total volumetric expansion at test pressure.
(3) Pressure testing. (i) For cylinders with a wall stress of 18,000 psig or less, the remaining cylinders of the lot must be pressure tested by the proof pressure, water-jacket, or direct expansion test method as defined in CGA C-1. The minimum test pressure must be maintained for the specific timeframe and the testing equipment must be calibrated as prescribed in CGA C-1. Further, all testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(ii) Each cylinder must be tested to a minimum of two (2) times service pressure and show no defect. If, due to failure of the test apparatus or operator error, the test pressure cannot be maintained, the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination of expansion properties is not required.
(4) Burst testing. One (1) finished cylinder selected at random out of each lot of 1000 or less must be hydrostatically tested to four (4) times service pressure without bursting. Inability to meet this requirement must result in rejection of the lot. All testing equipment and pressure indicating devices must be accurate within the parameters defined in CGA C-1.
(i) Flattening test. After hydrostatic testing, a flattening test is required on one section of a cylinder, taken at random out of each lot of 200 or less as follows:
(1) If the weld is not at midlength of the cylinder, the test section must be no less in width than 30 times the cylinder wall thickness. The weld must be in the center of the section. Weld reinforcement must be removed by machining or grinding so that the weld is flush with the exterior of the parent metal. There must be no evidence of cracking in the sample when it is flattened between flat plates to no more than 6 times the wall thickness.
(2) If the weld is at midlength of the cylinder, the test may be made as specified in paragraph (i)(1) of this section or must be made between wedge shaped knife edges (60° angle) rounded to a 1/2 inch radius. There must be no evidence of cracking in the sample when it is flattened to no more than 6 times the wall thickness.
(j) Mechanical test. A mechanical test must be conducted to determine yield strength, tensile strength, elongation as a percentage, and reduction of area of material as a percentage as follows:
(1) The test is required on two (2) specimens removed from one cylinder or part thereof as illustrated in appendix A to this subpart taken at random out of each lot of 200 or fewer.
(2) Specimens must conform to the following:
(i) A gauge length of 8 inches with a width not over 1 1/2 inches, a gauge length of 2 inches with a width not over 1 1/2 inches.
(ii) The specimen, exclusive of grip ends, may not be flattened. Grip ends may be flattened to within 1 inch of each end of the reduced section.
(iii) When size of cylinder does not permit securing straight specimens, the specimens may be taken in any location or direction and may be straightened or flattened cold, by pressure only, not by blows; when specimens are so taken and prepared, the inspector's report must show in connection with record of physical test detailed information in regard to such specimens.
(iv) Heating of a specimen for any purpose is not authorized.
(3) The yield strength in tension must be the stress corresponding to a permanent strain of 0.2 percent of the gauge length. The following conditions apply:
(i) The yield strength must be determined by the “offset” method as prescribed in ASTM E 8 (IBR, see § 171.7 of this subchapter).
(ii) Cross-head speed of the testing machine may not exceed 1/8 inch per minute during yield strength determination.
(k) Acceptable results for mechanical tests. An acceptable result of the mechanical test requires at least 7 percent and yield strength not over 80 percent of tensile strength.
(l) Weld tests. Welds of the cylinder are required to pass the following tests successfully:
(1) Reduced section tensile test. A specimen must be removed from the cylinder used for the mechanical tests specified in paragraph (j) of this section. The specimen must be taken from across the seam; edges must be parallel for a distance of approximately 2 inches on either side of the weld. The specimen must be fractured in tension. The actual breaking stress must be a minimum of 30,000 psi. The apparent breaking stress calculated on the minimum design wall thickness must be a minimum of two (2) times the stress calculated under paragraph (f)(2) of this section. If the specimen fails to meet the requirements, the lot must be rejected except that specimens may be taken from two (2) additional cylinders from the same lot as the previously tested specimens. If either of the latter specimens fails to meet requirements, the entire lot represented must be rejected.
(2) Guided bend test. A bend test specimen must be removed from the cylinder used for the mechanical test specified in paragraph (j) of this section. The specimen must be taken across the circumferential seam, must be a minimum of 1 1/2 inches wide, edges must be parallel and rounded with a file, and back-up strip, if used, must be removed by machining. The specimen must be tested as follows:
(i) Standard guided bend test. The specimen must be bent to refusal in the guided bend test jig as illustrated in CGA C-3 (IBR, see § 171.7 of this subchapter). The root of the weld (inside surface of the cylinder) must be located away from the ram of the jig. The specimen must not show a crack or other open defect exceeding 1/8 inch in any direction upon completion of the test. Should this specimen fail to meet the requirements, one additional specimen must be taken from two additional cylinders from the same lot and tested. If either of the latter specimens fails to meet requirements, the entire lot represented must be rejected.
(ii) Alternate guided bend test. This test may be used as an alternate to the guided bend test. The test specimen must be in conformance with The Aluminum Association's “Welding Aluminum: Theory and Practice, Fourth Edition, 2002” (IBR, see § 171.7 of this subchapter). If the specimen fails to meet the requirements, one additional specimen must be taken from two additional cylinders or welded test plates from the same lot and tested. If any of these latter two specimens fails to meet the requirements, the entire lot must be rejected.
(m) Rejected cylinders. Repair of welded seams is authorized. Acceptable cylinders must pass all prescribed tests.
(n) Markings. (1) Markings must be as required in § 178.35 and in addition must be stamped plainly and permanently in one of the following locations on the cylinder:
(i) On the neck, neckring, valve boss, valve protection sleeve, or similar part permanently attached to the top of the cylinder.
(ii) On the footring permanently attached to the cylinder, provided the water capacity of the cylinder does not exceed 30 pounds.
(2) Embossing the cylinder head or side wall is not permitted.
(o) Inspector's report. In addition to the information required by § 178.35, the record of chemical analyses must also include applicable information on iron, titanium, zinc, and magnesium used in the construction of the cylinder.
§ 178.69   Responsibilities and requirements for manufacturers of UN pressure receptacles.
(a) Each manufacturer of a UN pressure receptacle marked with “USA” as a country of approval must comply with the requirements in this section. The manufacturer must maintain a quality system, obtain an approval for each initial pressure receptacle design type, and ensure that all production of UN pressure receptacles meets the applicable requirements.
(1) Quality system. The manufacturer of a UN pressure receptacle must have its quality system approved by the Associate Administrator. The quality system will initially be assessed through an audit by the Associate Administrator or his or her representative to determine whether it meets the requirements of this section. The Associate Administrator will notify the manufacturer in writing of the results of the audit. The notification will contain the conclusions of the audit and any corrective action required. The Associate Administrator may perform periodic audits to ensure that the manufacturer operates in accordance with the quality system. Reports of periodic audits will be provided to the manufacturer. The manufacturer must bear the cost of audits.
(2) Quality system documentation. The manufacturer must be able to demonstrate a documented quality system. Management must review the adequacy of the quality system to assure that it is effective and conforms to the requirements in § 178.70. The quality system records must be in English and must include detailed descriptions of the following:
(i) The organizational structure and responsibilities of personnel with regard to design and product quality;
(ii) The design control and design verification techniques, processes, and procedures used when designing the pressure receptacles;
(iii) The relevant procedures for pressure receptacle manufacturing, quality control, quality assurance, and process operation instructions;
(iv) Inspection and testing methodologies, measuring and testing equipment, and calibration data;
(v) The process for meeting customer requirements;
(vi) The process for document control and document revision;
(vii) The system for controlling non-conforming material and records, including procedures for identification, segregation, and disposition;
(viii) Production, processing and fabrication, including purchased components, in-process and final materials; and
(ix) Training programs for relevant personnel.
(3) Maintenance of quality system. The manufacturer must maintain the quality system as approved by the Associate Administrator. The manufacturer shall notify the Associate Administrator of any intended changes to the approved quality system prior to making the change. The Associate Administrator will evaluate the proposed change to determine whether the amended quality system will satisfy the requirements. The Associate Administrator will notify the manufacturer of the findings.
(b) Design type approvals. The manufacturer must have each pressure receptacle design type reviewed by an IIA and approved by the Associate Administrator in accordance with § 178.70. A cylinder is considered to be of a new design, compared with an existing approved design, as stated in the applicable ISO design, construction and testing standard.
(c) Production inspection and certification. The manufacturer must ensure that each UN pressure receptacle is inspected and certified in accordance with § 178.71.
§ 178.70   Approval of UN pressure receptacles.
(a) Initial design-type approval. The manufacturer of a UN pressure receptacle must obtain an initial design type approval from the Associate Administrator. The initial design type approval must be of the pressure receptacle design as it is intended to be produced. The manufacturer must arrange for an IIA, approved by the Associate Administrator in accordance with subpart I of part 107 of this chapter, to perform a pre-audit of its pressure receptacle manufacturing operation prior to having an audit conducted by the Associate Administrator or his designee.
(b) IIA pre-audit. The manufacturer must submit an application for initial design type approval to the IIA for review. The IIA will examine the manufacturer's application for initial design type approval for completeness. An incomplete application will be returned to the manufacturer with an explanation. If an application is complete, the IIA will review all technical documentation, including drawings and calculations, to verify that the design meets all requirements of the applicable UN pressure receptacle standard and specification requirements. If the technical documentation shows that the pressure receptacle prototype design conforms to the applicable standards and requirements in § 178.70, the manufacturer will fabricate a prototype lot of pressure receptacles in conformance with the technical documentation representative of the design. The IIA will verify that the prototype lot conforms to the applicable requirements by selecting pressure receptacles and witnessing their testing. After prototype testing has been satisfactorily completed, showing the pressure receptacles fully conform to all applicable specification requirements, the certifying IIA must prepare a letter of recommendation and a design type approval certificate. The design type approval certificate must contain the name and address of the manufacturer and the IIA certifying the design type, the test results, chemical analyses, lot identification, and all other supporting data specified in the applicable ISO design, construction and testing standard. The IIA must provide the certificate and documentation to the manufacturer.
(c) Application for initial design type approval. If the pre-audit is found satisfactory by the IIA, the manufacturer will submit the letter of recommendation from the IIA and an application for design type approval to the Associate Administrator. An application for initial design type approval must be submitted for each manufacturing facility. The application must be in English and, at a minimum, contain the following information:
(1) The name and address of the manufacturing facility. If the application is submitted by an authorized representative on behalf of the manufacturer, the application must include the representative's name and address.
(2) The name and title of the individual responsible for the manufacturer's quality system, as required by § 178.69.
(3) The designation of the pressure receptacle and the relevant pressure receptacle standard.
(4) Details of any refusal of approval of a similar application by a designated approval agency of another country.
(5) The name and address of the production IIA that will perform the functions prescribed in paragraph (e) of this section. The IIA must be approved in writing by the Associate Administrator in accordance with subpart I of part 107 of this chapter.
(6) Documentation on the manufacturing facility as specified in § 178.69.
(7) Design specifications and manufacturing drawings, showing components and subassemblies if relevant, design calculations, and material specifications necessary to verify compliance with the applicable pressure receptacle design standard.
(8) Manufacturing procedures and any applicable standards that describe in detail the manufacturing processes and control.
(9) Design type approval test reports detailing the results of examinations and tests conducted in accordance with the relevant pressure receptacle standard, to include any additional data, such as suitability for underwater applications or compatibility with hydrogen embrittlement gases.
(d) Modification of approved pressure receptacle design type. Modification of an approved UN (ISO) pressure receptacle design type is not authorized without the approval of the Associate Administrator. However, modification of an approved UN (ISO) pressure receptacle design type is authorized without an additional approval of the Associate Administrator provided the design modification is covered under the UN (ISO) standard for the design type. A manufacturer seeking modification of an approved UN (ISO) pressure receptacle design type may be required to submit design qualification test data to the Associate Administrator before production. An audit may be required as part of the process to modify an approval.
(e) Responsibilities of the production IIA. The production IIA is responsible for ensuring that each pressure receptacle conforms to the design type approval. The production IIA must perform the following functions:
(1) Witness all inspections and tests specified in the UN pressure receptacle standard to ensure compliance with the standard and that the procedures adopted by the manufacturer meet the requirements of the standard;
(2) Verify that the production inspections were performed in accordance with this section;
(3) Select UN pressure receptacles from a prototype production lot and witness testing as required for the design type approval;
(4) Ensure that the various design type approval examinations and tests are performed accurately;
(5) Verify that each pressure receptacle is marked in accordance with the applicable requirements in § 178.71; and
(6) Furnish complete test reports to the manufacturer and upon request to the purchaser. The test reports and certificate of compliance must be retained by the IIA for at least 20 years from the original test date of the pressure receptacles.
(f) Production inspection audit and certification. (1) If the application, design drawing and quality control documents are found satisfactory, PHMSA will schedule an on-site audit of the pressure receptacle manufacturer's quality system, manufacturing processes, inspections, and test procedures.
(2) During the audit, the manufacturer will be required to produce pressure receptacles to the technical standards for which approval is sought.
(3) The production IIA must witness the required inspections and verifications on the pressure receptacles during the production run. The IIA selected by the manufacturer for production inspection and testing may be different from the IIA who performed the design type approval verifications.
(4) If the procedures and controls are deemed acceptable, test sample pressure receptacles will be selected at random from the production lot and sent to a laboratory designated by the Associate Administrator for verification testing.
(5) If the pressure receptacle test samples are found to conform to all the applicable requirements, the Associate Administrator will issue approvals to the manufacturer and the production IIA to authorize the manufacture of the pressure receptacles. The approved design type approval certificate will be returned to the manufacturer.
(6) Upon the receipt of the approved design type approval certificate from the Associate Administrator, the pressure receptacle manufacturer must sign the certificate.
(g) Recordkeeping. The production IIA and the manufacturer must retain a copy of the design type approval certificate and certificate of compliance records for at least 20 years.
(h) Denial of design type application. If the design type application is denied, the Associate Administrator will notify the applicant in writing and provide the reason for the denial. The manufacturer may request that the Associate Administrator reconsider the decision. The application request must—
(1) Be written in English and filed within 60 days of receipt of the decision;
(2) State in detail any alleged errors of fact and law; and
(3) Enclose any additional information needed to support the request to reconsider.
(i) Appeal. (1) A manufacturer whose reconsideration request is denied may appeal to the PHMSA Administrator. The appeal must—
(i) Be written in English and filed within 60 days of receipt of the Associate Administrator's decision on reconsideration;
(ii) State in detail any alleged errors of fact and law;
(iii) Enclose any additional information needed to support the appeal; and
(iv) State in detail the modification of the final decision sought.
(2) The PHMSA Administrator will grant or deny the relief and inform the appellant in writing of the decision. PHMSA Administrator's decision is the final administrative action.
(j) Termination of a design type approval certificate. (1) The Associate Administrator may terminate an approval certificate issue under this section if it is determined that, because of a change in circumstances, the approval no longer is needed or no longer would be granted if applied for; information upon which the approval was based is fraudulent or substantially erroneous; or termination of the approval is necessary to adequately protect against risks to life and property.
(2) Before an approval is terminated, the Associate Administrator will provide the manufacturer and the approval agency—
(i) Written notice of the facts or conduct believed to warrant the withdrawal;
(ii) Opportunity to submit oral and written evidence, and
(iii) Opportunity to demonstrate or achieve compliance with the application requirement.
(3) If the Associate Administrator determines that a certificate of approval must be withdrawn to preclude a significant and imminent adverse affect on public safety, the procedures in paragraph (j)(2)(ii) and (iii) of this section need not be provided prior to withdrawal of the approval, but shall be provided as soon as practicable thereafter.
§ 178.71   Specifications for UN pressure receptacles.
(a) General. Each UN pressure receptacle must meet the requirements of this section. UN pressure receptacles and service equipment constructed according to the standards applicable at the date of manufacture may continue in use subject to the continuing qualification and maintenance provisions of part 180 of this subchapter. Requirements for approval, qualification, maintenance, and testing are contained in § 178.70, and subpart C of part 180 of this subchapter.
(b) Definitions. The following definitions apply for the purposes of design and construction of UN pressure receptacles under this subpart:
Alternative arrangement means an approval granted by the Associate Administrator for a MEGC that has been designed, constructed or tested to the technical requirements or testing methods other than those specified for UN pressure receptacles in part 178 or part 180 of this subchapter.
Bundle of cylinders. See § 171.8 of this subchapter.
Design type means a pressure receptacle design as specified by a particular pressure receptacle standard.
Design type approval means an overall approval of the manufacturer's quality system and design type of each pressure receptacle to be produced within the manufacturer's facility.
UN tube. See § 171.8 of this subchapter.
(c) Following the final heat treatment, all cylinders, except those selected for batch testing must be subjected to a proof pressure or a hydraulic volumetric expansion test.
(d) Service equipment. (1) Except for pressure relief devices, UN pressure receptacle equipment, including valves, piping, fittings, and other equipment subjected to pressure must be designed and constructed to withstand at least 1.5 times the test pressure of the pressure receptacle.
(2) Service equipment must be configured, or designed, to prevent damage that could result in the release of the pressure receptacle contents during normal conditions of handling and transport. Manifold piping leading to shut-off valves must be sufficiently flexible to protect the valves and the piping from shearing or releasing the pressure receptacle contents. The filling and discharge valves and any protective caps must be secured against unintended opening. The valves must conform to ISO 10297:2014(E) and ISO 10297:2014/Amd 1:2017(E) (IBR, see § 171.7 of this subchapter), or for non-refillable pressure receptacles valves manufactured until December 31, 2020, ISO 13340:2001(E), and be protected as specified in § 173.301b(f) of this subchapter. Until December 31, 2022, the manufacture of a valve conforming to the requirements of ISO 10297:2014(E) is authorized. Until December 31, 2020, the manufacture of a valve conforming to the requirements in ISO 10297:2006(E) (IBR, see § 171.7 of this subchapter) was authorized. Until December 31, 2008, the manufacture of a valve conforming to the requirements in ISO 10297:1999(E) (IBR, see § 171.7 of this subchapter) was authorized. Additionally, valves must be initially inspected and tested in accordance with ISO 14246:2014(E) and ISO 14246:2014/Amd 1:2017(E), (IBR, see § 171.7 of this subchapter). For self-closing valves with inherent protection, the requirements of ISO 17879:2017(E) (IBR, see § 171.7 of this subchapter) shall be met until further notice.
(3) UN pressure receptacles that cannot be handled manually or rolled, must be equipped with devices (e.g., skids, rings, straps) ensuring that they can be safely handled by mechanical means and so arranged as not to impair the strength of, nor cause undue stresses, in the pressure receptacle.
(4) Pressure receptacles filled by volume must be equipped with a level indicator.
(e) Bundles of cylinders. UN pressure receptacles assembled in bundles must be structurally supported and held together as a unit and secured in a manner that prevents movement in relation to the structural assembly and movement that would result in the concentration of harmful local stresses. The frame design must ensure stability under normal operating conditions.
(1) The frame must securely retain all the components of the bundle and must protect them from damage during conditions normally incident to transportation. The method of cylinder restraint must prevent any vertical or horizontal movement or rotation of the cylinder that could cause undue strain on the manifold. The total assembly must be able to withstand rough handling, including being dropped or overturned.
(2) The frame must include features designed for the handling and transportation of the bundle. The lifting rings must be designed to withstand a design load of 2 times the maximum gross weight. Bundles with more than one lifting ring must be designed such that a minimum sling angle of 45 degrees to the horizontal can be achieved during lifting using the lifting rings. If four lifting rings are used, their design must be strong enough to allow the bundle to be lifted by two rings. Where two or four lifting rings are used, diametrically opposite lifting rings must be aligned with each other to allow for correct lifting using shackle pins. If the bundle is filled with forklift pockets, it must contain two forklift pockets on each side from which it is to be lifted. The forklift pockets must be positioned symmetrically consistent with the bundle center of gravity.
(3) The frame structural members must be designed for a vertical load of 2 times the maximum gross weight of the bundle. Design stress levels may not exceed 0.9 times the yield strength of the material.
(4) The frame must not contain any protrusions from the exterior frame structure that could cause a hazardous condition.
(5) The frame design must prevent collection of water or other debris that would increase the tare weight of bundles filled by weight.
(6) The floor of the bundle frame must not buckle during normal operating conditions and must allow for the drainage of water and debris from around the base of the cylinders.
(7) If the frame design includes movable doors or covers, they must be capable of being secured with latches or other means that will not become dislodged by operational impact loads. Valves that need to be operated in normal service or in an emergency must be accessible.
(8) For bundles of cylinders, pressure receptacle marking requirements only apply to the individual cylinders of a bundle and not to any assembly structure.
(f) Design and construction requirements for UN refillable welded cylinders and UN pressure drums. In addition to the general requirements of this section, UN refillable welded cylinders and UN pressure drums must conform to the following ISO standards, as applicable:
(1) ISO 4706: Gas cylinders—Refillable welded steel cylinders—Test pressure 60 bar and below (IBR, see § 171.7 of this subchapter).
(2) ISO 18172-1: Gas cylinders—Refillable welded stainless steel cylinders—Part 1: Test pressure 6 MPa and below (IBR, see § 171.7 of this subchapter).
(3) ISO 20703: Gas cylinders—Refillable welded aluminum-alloy cylinders—Design, construction and testing (IBR, see § 171.7 of this subchapter).
(4) ISO 21172-1:2015(E) Gas cylinders—Welded steel pressure drums up to 3,000 litres capacity for the transport of gases—Design and construction—Part 1: Capacities up-to 1,000 litres (IBR, see § 171.7 of this subchapter) in combination with ISO 21172-1:2015/Amd 1:2018(E)—Gas Cylinders—Welded steel pressure drums up to 3,000 litres capacity for the transport of gases—Design and construction—Part 1: Capacities up—to 1,000 litres—Amendment 1 (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the use of ISO 21172-1:2015 (IBR, see § 171.7 of this subchapter) without the supplemental amendment is authorized.
(g) Design and construction requirements for UN refillable seamless steel cylinders. In addition to the general requirements of this section, UN refillable seamless steel cylinders must conform to the following ISO standards, as applicable:
(1) ISO 9809-1:2019(E), Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than 1100 MPa (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-1:2010(E) (IBR, see § 171.7 of this subchapter) is authorized.
(2) ISO 9809-2:2019(E), Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 2: Quenched and tempered steel cylinders and tubes with tensile strength greater than or equal to 1100 MPa (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-2:2010 (IBR, see § 171.7 of this subchapter) is authorized.
(3) ISO 9809-3:2019(E), Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 3: Normalized steel cylinders and tubes. (IBR, see § 171.7 of this subchapter). Until December 31, 2026, a cylinder may instead conform to ISO 9809-3:2010(E) (IBR, see § 171.7 of this subchapter).
(4) ISO 9809-4:2014(E), Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 4: Stainless steel cylinders with an Rm value of less than 1,100 MPa (IBR, see § 171.7 of this subchapter).
(h) Design and construction requirements for UN refillable seamless aluminum alloy cylinders. In addition to the general requirements of this section, UN refillable seamless aluminum cylinders must conform to ISO 7866:2012(E) as modified by ISO 7866:2012/Cor.1:2014(E) (IBR, see § 171.7 of this subchapter). Until December 31, 2020, the manufacture of a cylinder conforming to the requirements in ISO 7866(E) (IBR, see § 171.7 of this subchapter) is authorized. The use of Aluminum alloy 6351-T6 or equivalent is prohibited.
(i) Design and construction requirements for UN non-refillable metal cylinders. In addition to the general requirements of this section, UN non-refillable metal cylinders must conform to ISO 11118:2015(E) Gas cylinders—Non-refillable metallic gas cylinders—Specification and test methods, in combination with ISO 11118:2015/Amd 1:2019 Gas cylinders—Non-refillable metallic gas cylinders—Specification and test methods—Amendment 1. (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the use of ISO 11118:2015 (IBR, see § 171.7 of this subchapter) without the supplemental amendment is authorized.
(j) Design and construction requirements for UN refillable seamless steel tubes. In addition to the general requirements of this section, UN refillable seamless steel tubes must conform to ISO 11120:2015(E) Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and 3,000 L—Design, construction and testing (IBR, see § 171.7 of this subchapter). Until December 31, 2022, UN refillable seamless steel tubes may be manufactured in accordance with ISO 11120: Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and 3,000 L—Design, construction and testing (IBR, see § 171.7 of this subchapter)
(k) Design and construction requirements for UN acetylene cylinders. In addition to the general requirements of this section, UN acetylene cylinders must conform to the following ISO standards, as applicable:
(1) For the cylinder shell:
(i) ISO 9809-1:2019(E) Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than 1100 MPa (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-1:2010(E) (IBR, see § 171.7 of this subchapter) is authorized.
(ii) ISO 9809-3:2019(E) Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 3: Normalized steel cylinders and tubes (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-3:2010(E) (IBR, see § 171.7 of this subchapter) is authorized.
(2) The porous mass in an acetylene cylinder must conform to ISO 3807:2013(E) (IBR, see § 171.7 of this subchapter). Until December 31, 2020, the manufacture of a cylinder conforming to the requirements in ISO 3807-2(E) (IBR, see § 171.7 of this subchapter) is authorized.
(l) Design and construction requirements for UN composite cylinders and tubes. (1) In addition to the general requirements of this section, UN composite cylinders and tubes must be designed for a design life of not less than 15 years. Composite cylinders and tubes with a design life longer than 15 years must not be filled after 15 years from the date of manufacture, unless the design has successfully passed a service life test program. The service life test program must be part of the initial design type approval and must specify inspections and tests to demonstrate that cylinders manufactured accordingly remain safe to the end of their design life. The service life test program and the results must be approved by the competent authority of the country of approval that is responsible for the initial approval of the cylinder design. The service life of a composite cylinder or tube must not be extended beyond its initial approved design life. Additionally, composite cylinders and tubes must conform to the following ISO standards, as applicable:
(i) ISO 11119-1:2012(E) (IBR, see § 171.7 of this subchapter). Until December 31, 2020, cylinders conforming to the requirements in ISO 11119-1(E), (IBR, see § 171.7 of this subchapter) are authorized.
(ii) ISO 11119-2:2012(E) (ISO 11119-2:2012/Amd.1:2014(E)) (IBR, see § 171.7 of this subchapter). Until December 31, 2020, cylinders conforming to the requirements in ISO 11119-2(E) (IBR, see § 171.7 of this subchapter) are authorized.
(iii) ISO 11119-3:2013(E) (IBR, see § 171.7 of this subchapter). Until December 31, 2020, cylinders conforming to the requirements in ISO 11119-3(E) (IBR, see § 171.7 of this subchapter) are authorized.
(iv) ISO 11119-4:2016(E) (IBR, see § 171.7 of this subchapter).
(2) ISO 11119-2 and ISO 11119-3 gas cylinders of composite construction manufactured in accordance with the requirements for underwater use must bear the “UW” mark.
(m) Design and construction requirements for UN metal hydride storage systems. In addition to the general requirements of this section, metal hydride storage systems must conform to ISO 16111:2018(E) Transportable gas storage devices—Hydrogen absorbed in reversible metal hydride (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a UN metal hydride storage system conforming to the requirements in ISO 16111:2008 (IBR, see § 171.7 of this subchapter) is authorized.
(n) Design and construction requirements for UN cylinders for the transportation of adsorbed gases. In addition to the general requirements of this section, UN cylinders for the transportation of adsorbed gases must conform to the following ISO standards, as applicable:
(1) ISO 11513:2019, Gas cylinders—Refillable welded steel cylinders containing materials for sub-atmospheric gas packaging (excluding acetylene)—Design, construction, testing, use and periodic inspection (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 11513:2011(E) (IBR, see § 171.7 of this subchapter) is authorized.
(2) ISO 9809-1:2019(E): Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than 1100 MPa (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-1:2010(E) (IBR, see § 171.7 of this subchapter is authorized.
(o) Material compatibility. In addition to the material requirements specified in the UN pressure receptacle design and construction ISO standards, and any restrictions specified in part 173 for the gases to be transported, the requirements of the following standards must be applied with respect to material compatibility:
(1) ISO 11114-1:2012(E) and 11114-1:2012/Amd 1:2017(E) (IBR, see § 171.7 of this subchapter).
(2) ISO 11114-2:2013(E) (IBR, see § 171.7 of this subchapter).
(p) Protection of closures. Closures and their protection must conform to the requirements in § 173.301(f) of this subchapter.
(q) Marking of UN refillable pressure receptacles. UN refillable pressure receptacles must be marked clearly and legibly. The required markings must be permanently affixed by stamping, engraving, or other equivalent method, on the shoulder, top end or neck of the pressure receptacle or on a permanently affixed component of the pressure receptacle, such as a welded collar. Except for the “UN” mark, the minimum size of the marks must be 5 mm for pressure receptacles with a diameter greater than or equal to 140 mm, and 2.5 mm for pressure receptacles with a diameter less than 140 mm. The minimum size of the “UN” mark must be 5 mm for pressure receptacles with a diameter less than 140 mm, and 10 mm for pressure receptacles with a diameter of greater than or equal to 140 mm. The depth of the markings must not create harmful stress concentrations. A refillable pressure receptacle conforming to the UN standard must be marked as follows:
(1) The UN packaging symbol.
(2) The ISO standard, for example ISO 9809-1, used for design, construction and testing. Acetylene cylinders must be marked to indicate the porous mass and the steel shell, for example: “ISO 3807-2/ISO 9809-1.”
(3) The mark of the country where the approval is granted. The letters “USA” must be marked on UN pressure receptacles approved by the United States. The manufacturer must obtain an approval number from the Associate Administrator. The manufacturer approval number must follow the country of approval mark, separated by a slash (for example, USA/MXXXX). Pressure receptacles approved by more than one national authority may contain the mark of each country of approval, separated by a comma.
(4) The identity mark or stamp of the IIA.
(5) The date of the initial inspection, the year (four digits) followed by the month (two digits) separated by a slash, for example “2006/04”.
(6) The test pressure in bar, preceded by the letters “PH” and followed by the letters “BAR”.
(7) The rated charging pressure of the metal hydride storage system in bar, preceded by the letters “RCP” and followed by the letters “BAR.”
(8) The empty or tare weight. Except for acetylene cylinders, empty weight is the mass of the pressure receptacle in kilograms, including all integral parts (e.g., collar, neck ring, foot ring, etc. ), followed by the letters “KG”. The empty weight does not include the mass of the valve, valve cap or valve guard or any coating. The empty weight must be expressed to three significant figures rounded up to the last digit. For cylinders of less than 1 kg, the empty weight must be expressed to two significant figures rounded down to the last digit. For acetylene cylinders, the tare weight must be marked on the cylinders in kilograms. The tare weight is the sum of the empty weight, mass of the valve, any coating and all permanently attached parts (e.g., fittings and accessories) that are not removed during filling. The tare weight must be expressed to two significant figures rounded down to the last digit. The tare weight does not include the cylinder cap or any outlet cap or plug not permanently attached to the cylinder.
(9) The minimum wall thickness of the pressure receptacle in millimeters followed by the letters “MM”. This mark is not required for pressure receptacles with a water capacity less than or equal to 1.0 L or for composite cylinders.
(10) For pressure receptacles intended for the transport of compressed gases and UN 1001 acetylene, dissolved, the working pressure in bar, proceeded by the letters “PW”.
(11) For liquefied gases, the water capacity in liters expressed to three significant digits rounded down to the last digit, followed by the letter “L”. If the value of the minimum or nominal water capacity is an integer, the digits after the decimal point may be omitted.
(12) Identification of the cylinder thread type ( e.g., 25E). Information on the marks that may be used for identifying threads for cylinders is given in ISO/TR 11364, Gas Cylinders—Compilation of national and international valve stem/gas cylinder neck threads and their identification and marking system (IBR, see § 171.7 of this subchapter).
(13) The country of manufacture. The letters “USA” must be marked on cylinders manufactured in the United States.
(14) The serial number assigned by the manufacturer.
(15) For steel pressure receptacles, the letter “H” showing compatibility of the steel, as specified in ISO 11114-1.
(16) Identification of aluminum alloy, if applicable.
(17) Stamp for nondestructive testing, if applicable.
(18) Stamp for underwater use of composite cylinders, if applicable.
(19) For metal hydride storage systems having a limited life, the date of expiration indicated by the word “FINAL,” followed by the year (four digits), the month (two digits) and separated by a slash.
(20) For composite cylinders and tubes having a limited design life, the letters “FINAL” followed by the design life shown as the year (four digits) followed by the month (two digits) separated by a slash ( i.e. “/”).
(21) For composite cylinders and tubes having a limited design life greater than 15 years and for composite cylinders and tubes having non-limited design life, the letters “SERVICE” followed by the date 15 years from the date of manufacture (initial inspection) shown as the year (four digits) followed by the month (two digits) separated by a slash ( i.e. “/”).
(r) Marking sequence. The marking required by paragraph (q) of this section must be placed in three groups as shown in the example below:
(1) The top grouping contains manufacturing marks and must appear consecutively in the sequence given in paragraphs (q)(13) through (19) of this section.
(2) The middle grouping contains operational marks described in paragraphs (q)(6) through (11) of this section.
(3) The bottom grouping contains certification marks and must appear consecutively in the sequence given in paragraphs (q)(1) through (5) of this section.
(s) Other markings. Other markings are allowed in areas other than the side wall, provided they are made in low stress areas and are not of a size and depth that will create harmful stress concentrations. Such marks must not conflict with required marks.
(t) Marking of UN non-refillable pressure receptacles. Unless otherwise specified in this paragraph, each UN non-refillable pressure receptacle must be clearly and legibly marked as prescribed in paragraph (q) of this section. In addition, permanent stenciling is authorized. Except when stenciled, the marks must be on the shoulder, top end or neck of the pressure receptacle or on a permanently affixed component of the pressure receptacle (e.g., a welded collar).
(1) The marking requirements and sequence listed in paragraphs (q)(1) through (19) of this section are required, except the markings in paragraphs (q)(8), (9), (12) and (18) are not applicable. The required serial number marking in paragraph (q)(14) may be replaced by the batch number.
(2) Each receptacle must be marked with the words “DO NOT REFILL” in letters of at least 5 mm in height.
(3) A non-refillable pressure receptacle, because of its size, may substitute the marking required by this paragraph with a label. Reduction in marking size is authorized only as prescribed in ISO 7225, Gas cylinders—Precautionary labels. (IBR, see § 171.7 of this subchapter).
(4) Each non-refillable pressure receptacle must also be legibly marked by stenciling the following statement: “Federal law forbids transportation if refilled-penalty up to $500,000 fine and 5 years in imprisonment (49 U.S.C. 5124).”
(u) Marking of bundles of cylinders. (1) Individual cylinders in a bundle of cylinders must be marked in accordance with paragraphs (q), (r), (s) and (t) of this section as appropriate.
(2) Refillable UN bundles of cylinders must be marked clearly and legibly with certification, operational, and manufacturing marks. These marks must be permanently affixed (e.g., stamped, engraved, or etched) on a plate permanently attached to the frame of the bundle of cylinders. Except for the “UN” mark, the minimum size of the marks must be 5 mm. The minimum size of the “UN” mark must be 10 mm. A refillable UN bundle of cylinders must be marked with the following:
(i) The UN packaging symbol;
(ii) The ISO standard, for example ISO 9809-1, used for design, construction and testing. Acetylene cylinders must be marked to indicate the porous mass and the steel shell, for example: “ISO 3807-2/ISO 9809-1”;
(iii) The mark of the country where the approval is granted. The letters “USA” must be marked on UN pressure receptacles approved by the United States. The manufacturer must obtain an approval number from the Associate Administrator. The manufacturer approval number must follow the country of approval mark, separated by a slash (for example, USA/MXXXX). Pressure receptacles approved by more than one national authority may contain the mark of each country of approval, separated by a comma;
(iv) The identity mark or stamp of the IIA;
(v) The date of the initial inspection, the year in four digits followed by the two digit month separated by a slash, for example “2006/04”;
(vi) The test pressure in bar, preceded by the letters “PH” and followed by the letters “BAR”;
(vii) For pressure receptacles intended for the transport of compressed gases and UN 1001 acetylene, dissolved, the working pressure in bar, proceeded by the letters “PW”;
(viii) For liquefied gases, the water capacity in liters expressed to three significant digits rounded down to the last digit, followed by the letter “L”. If the value of the minimum or nominal water capacity is an integer, the digits after the decimal point may be omitted;
(ix) The total mass of the frame of the bundle and all permanently attached parts (cylinders, manifolds, fittings and valves). Bundles intended for the carriage of UN 1001 acetylene, dissolved must bear the tare mass as specified in clause N.4.2 of ISO 10961:2010;
(x) The country of manufacture. The letters “USA” must be marked on cylinders manufactured in the United States;
(xi) The serial number assigned by the manufacturer; and
(xii) For steel pressure receptacles, the letter “H” showing compatibility of the steel, as specified in 1SO 11114-1.
(v) Marking sequence. The marking required by paragraph (u) of this section must be placed in three groups as follows:
(1) The top grouping contains manufacturing marks and must appear consecutively in the sequence given in paragraphs (u)(2)(x) through (u)(2)(xii) of this section as applicable.
(2) The middle grouping contains operational marks described in paragraphs (u)(2)(vi) through (u)(2)(ix) of this section as applicable. When the operational mark specified in paragraph (u)(2)(vii) is required, it must immediately precede the operational mark specified in paragraph (u)(2)(vi).
(3) The bottom grouping contains certification marks and must appear consecutively in the sequence given in paragraphs (u)(2)(i) through (u)(2)(v) of this section as applicable.
§ 178.74   Approval of MEGCs.
(a) Application for design type approval. (1) Each new MEGC design type must have a design approval certificate. An owner or manufacturer must apply to an approval agency that is approved by the Associate Administrator in accordance with subpart E of part 107 of this chapter + to obtain approval of a new design. When a series of MEGCs is manufactured without change in the design, the certificate is valid for the entire series. The design approval certificate must refer to the prototype test report, the materials of construction of the manifold, the standards to which the pressure receptacles are made and an approval number. The compliance requirements or test methods applicable to MEGCs as specified in this subpart may be varied when the level of safety is determined to be equivalent to or exceed the requirements of this subchapter and is approved in writing by the Associate Administrator. A design approval may serve for the approval of smaller MEGCs made of materials of the same type and thickness, by the same fabrication techniques and with identical supports, equivalent closures and other appurtenances.
(2) Each application for design approval must be in English and contain the following information:
(i) Two complete copies of all engineering drawings, calculations, and test data necessary to ensure that the design meets the relevant specification.
(ii) The manufacturer's serial number that will be assigned to each MEGC.
(iii) A statement as to whether the design type has been examined by any approval agency previously and judged unacceptable. Affirmative statements must be documented with the name of the approval agency, reason for non-acceptance, and the nature of modifications made to the design type.
(b) Actions by the approval agency. The approval agency must review the application for design type approval, including all drawings and calculations, to ensure that the design of the MEGC meets all requirements of the relevant specification and to determine whether it is complete and conforms to the requirements of this section. An incomplete application will be returned to the applicant with the reasons why the application was returned. If the application is complete and all applicable requirements of this section are met, the approval agency must prepare a MEGC design approval certificate containing the manufacturer's name and address, results and conclusions of the examination and necessary data for identification of the design type. If the Associate Administrator approves the Design Type Approval Certificate application, the approval agency and the manufacturer must each maintain a copy of the approved drawings, calculations, and test data for at least 20 years.
(c) Approval agency's responsibilities. The approval agency is responsible for ensuring that the MEGC conforms to the design type approval. The approval agency must:
(1) Witness all tests required for the approval of the MEGC specified in this section and § 178.75.
(2) Ensure, through appropriate inspection, that each MEGC is fabricated in all respects in conformance with the approved drawings, calculations, and test data.
(3) Determine and ensure that the MEGC is suitable for its intended use and that it conforms to the requirements of this subchapter.
(4) Apply its name, identifying mark or identifying number, and the date the approval was issued, to the metal identification marking plate attached to the MEGC upon successful completion of all requirements of this subpart. Any approvals by the Associate Administrator authorizing design or construction alternatives (Alternate Arrangements) of the MEGC (see paragraph (a) of this section) must be indicated on the metal identification plate as specified in § 178.75(j).
(5) Prepare an approval certificate for each MEGC or, in the case of a series of identical MEGCs manufactured to a single design type, for each series of MEGCs. The approval certificate must include all of the following information:
(i) The information displayed on the metal identification plate required by § 178.75(j);
(ii) The results of the applicable framework test specified in ISO 1496-3 (IBR, see § 171.7 of this subchapter);
(iii) The results of the initial inspection and test specified in paragraph (h) of this section;
(iv) The results of the impact test specified in § 178.75(i)(4);
(v) Certification documents verifying that the cylinders and tubes conform to the applicable standards; and
(vi) A statement that the approval agency certifies the MEGC in accordance with the procedures in this section and that the MEGC is suitable for its intended purpose and meets the requirements of this subchapter. When a series of MEGCs is manufactured without change in the design type, the certificate may be valid for the entire series of MEGCs representing a single design type. The approval number must consist of the distinguishing sign or mark of the country (“USA” for the United States of America) where the approval was granted and a registration number.
(6) Retain on file a copy of each approval certificate for at least 20 years.
(d) Manufacturers' responsibilities. The manufacturer is responsible for compliance with the applicable specifications for the design and construction of MEGCs. The manufacturer of a MEGC must:
(1) Comply with all the requirements of the applicable ISO standard specified in § 178.71;
(2) Obtain and use an approval agency to review the design, construction and certification of the MEGC;
(3) Provide a statement in the manufacturers' data report certifying that each MEGC manufactured complies with the relevant specification and all the applicable requirements of this subchapter; and
(4) Retain records for the MEGCs for at least 20 years. When required by the specification, the manufacturer must provide copies of the records to the approval agency, the owner or lessee of the MEGC, and to a representative of DOT, upon request.
(e) Denial of application for approval. If the Associate Administrator finds that the MEGC will not be approved for any reason, the Associate Administrator will notify the applicant in writing and provide the reason for the denial. The manufacturer may request that the Associate Administrator reconsider the decision. The application request must—
(1) Be written in English and filed within 90 days of receipt of the decision;
(2) State in detail any alleged errors of fact and law; and
(3) Enclose any additional information needed to support the request to reconsider.
(f) Appeal. (1) A manufacturer whose reconsideration request is denied may appeal to the PHMSA Administrator. The appeal must—
(i) Be in writing and filed within 90 days of receipt of the Associate Administrator s decision on reconsideration;
(ii) State in detail any alleged errors of fact and law;
(iii) Enclose any additional information needed to support the appeal; and
(iv) State in detail the modification of the final decision sought.
(2) The Administrator will grant or deny the relief and inform the appellant in writing of the decision. The Administrator's decision is the final administrative action.
(g) Modifications to approved MEGCs. (1) Prior to modification of any approved MEGC that may affect conformance and safe use, and that may involve a change to the design type or affect its ability to retain the hazardous material in transportation, the MEGC's owner must inform the approval agency that prepared the initial approval certificate for the MEGC or, if the initial approval agency is unavailable, another approval agency, of the nature of the modification and request certification of the modification. The owner must supply the approval agency with all revised drawings, calculations, and test data relative to the intended modification. The MEGC's owner must also provide a statement as to whether the intended modification has been examined and determined to be unacceptable by any approval agency. The written statement must include the name of the approval agency, the reason for non-acceptance, and the nature of changes made to the modification since its original rejection.
(2) The approval agency must review the request for modification. If the approval agency determines that the proposed modification does not conform to the relevant specification, the approval agency must reject the request in accordance with paragraph (d) of this section. If the approval agency determines that the proposed modification conforms fully with the relevant specification, the request is accepted. If modification to an approved MEGC alters any information on the approval certificate, the approval agency must prepare a new approval certificate for the modified MEGC and submit the certificate to the Associate Administrator for approval. After receiving approval from the Associate Administrator, the approval agency must ensure that any necessary changes are made to the metal identification plate. A copy of each newly issued approval certificate must be retained by the approval agency and the MEGC's owner for at least 20 years. The approval agency must perform the following activities:
(i) Retain a set of the approved revised drawings, calculations, and data as specified in § 178.69(b)(4) for at least 20 years;
(ii) Ensure through appropriate inspection that all modifications conform to the revised drawings, calculations, and test data; and
(iii) Determine the extent to which retesting of the modified MEGC is necessary based on the nature of the proposed modification, and ensure that all required retests are satisfactorily performed.
(h) Termination of Approval Certificate. (1) The Associate Administrator may terminate an approval issued under this section if he or she determines that—
(i) Because of a change in circumstances, the approval no longer is needed or no longer would be granted if applied for;
(ii) Information upon which the approval was based is fraudulent or substantially erroneous;
(iii) Termination of the approval is necessary to adequately protect against risks to life and property; or
(iv) The MEGC does not meet the specification.
(2) Before an approval is terminated, the Associate Administrator will provide the person—
(i) Written notice of the facts or conduct believed to warrant the termination;
(ii) An opportunity to submit oral and written evidence; and
(3) An opportunity to demonstrate or achieve compliance with the applicable requirements.
(i) Imminent Danger. If the Associate Administrator determines that a certificate of approval must be terminated to preclude a significant and imminent adverse effect on public safety, the Associate Administrator may terminate the certificate immediately. In such circumstances, the opportunities of paragraphs (h)(2) and (3) of this section need not be provided prior to termination of the approval, but must be provided as soon as practicable thereafter.
§ 178.75   Specifications for MEGCs.
(a) General. Each MEGC must meet the requirements of this section. In a MEGC that meets the definition of a “container” within the terms of the International Convention for Safe Containers (CSC) must meet the requirements of the CSC as amended and 49 CFR parts 450 through 453, and must have a CSC approval plate.
(b) Alternate Arrangements. The technical requirements applicable to MEGCs may be varied when the level of safety is determined to be equivalent to or exceed the requirements of this subchapter. Such an alternate arrangement must be approved in writing by the Associate Administrator. MEGCs approved to an Alternate Arrangement must be marked as required by paragraph (j) of this section.
(c) Definitions. The following definitions apply:
Leakproofness test means a test using gas subjecting the pressure receptacles and the service equipment of the MEGC to an effective internal pressure of not less than 20% of the test pressure.
Manifold means an assembly of piping and valves connecting the filling and/or discharge openings of the pressure receptacles.
Maximum permissible gross mass or MPGM means the heaviest load authorized for transport (sum of the tare mass of the MEGC, service equipment and pressure receptacle).
Service equipment means manifold system (measuring instruments, piping and safety devices).
Shut-off valve means a valve that stops the flow of gas.
Structural equipment means the reinforcing, fastening, protective and stabilizing members external to the pressure receptacles.
(d) General design and construction requirements. (1) The MEGC must be capable of being loaded and discharged without the removal of its structural equipment. It must possess stabilizing members external to the pressure receptacles to provide structural integrity for handling and transport. MEGCs must be designed and constructed with supports to provide a secure base during transport and with lifting and tie-down attachments that are adequate for lifting the MEGC including when loaded to its maximum permissible gross mass. The MEGC must be designed to be loaded onto a transport vehicle or vessel and equipped with skids, mountings or accessories to facilitate mechanical handling.
(2) MEGCs must be designed, manufactured and equipped to withstand, without loss of contents, all normal handling and transportation conditions. The design must take into account the effects of dynamic loading and fatigue.
(3) Each pressure receptacle of a MEGC must be of the same design type, seamless steel, or composite, and constructed and tested according to one of the following ISO standards:
(i) ISO 9809-1:2019(E), Gas cylinders—Refillable seamless steel gas cylinders—Design, construction, and testing—Part 1: Quenched and tempered steel cylinders with tensile strength less than 1100 MPa (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-1:2010(E) (IBR, see § 171.7 of this subchapter) is authorized.
(ii) ISO 9809-2:2019(E), Gas cylinders—Design, construction and testing of refillable seamless steel gas cylinders and tubes—Part 2: Quenched and tempered steel cylinders and tubes with tensile strength greater than or equal to 1100 MPa (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in \ ISO 9809-2:2010(E) (IBR, see § 171.7 of this subchapter) is authorized.
(iii) ISO 9809-3:2019(E), Gas cylinders—Design, construction, and testing of refillable seamless steel gas cylinders and tubes—Part 3: Normalized steel cylinders and tubes (IBR, see § 171.7 of this subchapter). Until December 31, 2026, the manufacture of a cylinder conforming to the requirements in ISO 9809-3:2010(E) (IBR, see § 171.7 of this subchapter) is authorized.
(iv) ISO 9809-4:2014(E) Gas cylinders—Refillable seamless steel gas cylinders—Design, construction and testing—Part 4: Stainless steel cylinders with an Rm value of less than 1 100 MPa (IBR, see § 171.7 of this subchapter).
(v) ISO 11120:2015(E) Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and 3000 L—Design, construction and testing (IBR, see § 171.7 of this subchapter). Until December 31, 2022, pressure receptacles of a MEGC may be constructed and tested in accordance with ISO 11120:1999(E) Gas cylinders—Refillable seamless steel tubes of water capacity between 150 L and 3000 L—Design, construction and testing (IBR, see § 171.7 of this subchapter).
(vi) ISO 11119-1:2012(E), Gas cylinders—Refillable composite gas cylinders and tubes—Design, construction and testing—Part 1: Hoop wrapped fibre reinforced composite gas cylinders and tubes up to 450 l (IBR, see § 171.7 of this subchapter).
(vii) ISO 11119-2:2012(E) and ISO 11119-2:2012/Amd.1:2014(E), Gas cylinders—Refillable composite gas cylinders and tubes—Design, construction and testing—Part 2: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with load-sharing metal liners (both IBR, see § 171.7 of this subchapter).
(viii) ISO 11119-3:2013(E) Gas cylinders—Refillable composite gas cylinders and tubes—Design, construction and testing—Part 3: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with non-load-sharing metallic or non-metallic liners (IBR, see § 171.7 of this subchapter).
(ix) ISO 11119-4:2016(E) Gas cylinders—Refillable composite gas cylinders—Design, construction and testing—Part 4: Fully wrapped fibre reinforced composite gas cylinders up to 150 l with load-sharing welded metallic liners (IBR, see § 171.7 of this subchapter).
(4) Pressure receptacles of MEGCs, fittings, and pipework must be constructed of a material that is compatible with the hazardous materials intended to be transported, as specified in this subchapter.
(5) Contact between dissimilar metals that could result in damage by galvanic action must be prevented by appropriate means.
(6) The materials of the MEGC, including any devices, gaskets, and accessories, must have no adverse effect on the gases intended for transport in the MEGC.
(7) MEGCs must be designed to withstand, without loss of contents, at least the internal pressure due to the contents, and the static, dynamic and thermal loads during normal conditions of handling and transport. The design must take into account the effects of fatigue, caused by repeated application of these loads through the expected life of the MEGC.
(8) MEGCs and their fastenings must, under the maximum permissible load, be capable of withstanding the following separately applied static forces (for calculation purposes, acceleration due to gravity (g) = 9.81 m/s 2 ):
(i) In the direction of travel: 2g (twice the MPGM multiplied by the acceleration due to gravity);
(ii) Horizontally at right angles to the direction of travel: 1g (the MPGM multiplied by the acceleration due to gravity. When the direction of travel is not clearly determined, the forces must be equal to twice the MPGM);
(iii) Vertically upwards: 1g (the MPGM multiplied by the acceleration due to gravity); and
(iv) Vertically downwards: 2g (twice the MPGM (total loading including the effect of gravity) multiplied by the acceleration due to gravity.
(9) Under each of the forces specified in paragraph (d)(8) of this section, the stress at the most severely stressed point of the pressure receptacles must not exceed the values given in the applicable design specifications (e.g., ISO 11120).
(10) Under each of the forces specified in paragraph (d)(8) of this section, the safety factor for the framework and fastenings must be as follows:
(i) For steels having a clearly defined yield point, a safety factor of 1.5 in relation to the guaranteed yield strength; or
(ii) For steels with no clearly defined yield point, a safety factor of 1.5 in relation to the guaranteed 0.2 percent proof strength and, for austenitic steels, the 1 percent proof strength.
(11) MEGCs must be capable of being electrically grounded to prevent electrostatic discharge when intended for flammable gases.
(12) The pressure receptacles of a MEGC must be secured in a manner to prevent movement that could result in damage to the structure and concentration of harmful localized stresses.
(e) Service equipment. (1) Service equipment must be arranged so that it is protected from mechanical damage by external forces during handling and transportation. When the connections between the frame and the pressure receptacles allow relative movement between the subassemblies, the equipment must be fastened to allow movement to prevent damage to any working part. The manifolds, discharge fittings (pipe sockets, shut-off devices), and shut-off valves must be protected from damage by external forces. Manifold piping leading to shut-off valves must be sufficiently flexible to protect the valves and the piping from shearing, or releasing the pressure receptacle contents. The filling and discharge devices, including flanges or threaded plugs, and any protective caps must be capable of being secured against unintended opening.
(2) Each pressure receptacle intended for the transport of Division 2.3 gases must be equipped with an individual shut-off valve. The manifold for Division 2.3 liquefied gases must be designed so that each pressure receptacle can be filled separately and be kept isolated by a valve capable of being closed during transit. For Division 2.1 gases, the pressure receptacles must be isolated by an individual shut-off valve into assemblies of not more than 3,000 L.
(3) For MEGC filling and discharge openings:
(i) Two valves in series must be placed in an accessible position on each discharge and filling pipe. One of the valves may be a backflow prevention valve.
(ii) The filling and discharge devices may be equipped to a manifold.
(iii) For sections of piping which can be closed at both ends and where a liquid product can be trapped, a pressure-relief valve must be provided to prevent excessive pressure build-up.
(iv) The main isolation valves on a MEGC must be clearly marked to indicate their directions of closure. All shutoff valves must close by a clockwise motion of the handwheel.
(v) Each shut-off valve or other means of closure must be designed and constructed to withstand a pressure equal to or greater than 1.5 times the test pressure of the MEGC.
(vi) All shut-off valves with screwed spindles must close by a clockwise motion of the handwheel. For other shut-off valves, the open and closed positions and the direction of closure must be clearly shown.
(vii) All shut-off valves must be designed and positioned to prevent unintentional opening.
(viii) Ductile metals must be used in the construction of valves or accessories.
(4) The piping must be designed, constructed and installed to avoid damage due to expansion and contraction, mechanical shock and vibration. Joints in tubing must be brazed or have an equally strong metal union. The melting point of brazing materials must be no lower than 525 °C (977 °F). The rated pressure of the service equipment and of the manifold must be not less than two-thirds of the test pressure of the pressure receptacles.
(f) Pressure relief devices. Each pressure receptacle must be equipped with one or more pressure relief devices as specified in § 173.301(f) of this subchapter. When pressure relief devices are installed, each pressure receptacle or group of pressure receptacles of a MEGC that can be isolated must be equipped with one or more pressure relief devices. Pressure relief devices must be of a type that will resist dynamic forces including liquid surge and must be designed to prevent the entry of foreign matter, the leakage of gas and the development of any dangerous excess pressure.
(1) The size of the pressure relief devices: CGA S-1.1, excluding paragraph 9.1.1, (IBR, see § 171.7 of this subchapter) must be used to determine the relief capacity of individual pressure receptacles.
(2) Connections to pressure-relief devices: Connections to pressure relief devices must be of sufficient size to enable the required discharge to pass unrestricted to the pressure relief device. A shut-off valve installed between the pressure receptacle and the pressure relief device is prohibited, except where duplicate devices are provided for maintenance or other reasons, and the shut-off valves serving the devices actually in use are locked open, or the shut-off valves are interlocked so that at least one of the duplicate devices is always operable and capable of meeting the requirements of paragraph (f)(1) of this section. No obstruction is permitted in an opening leading to or leaving from a vent or pressure-relief device that might restrict or cut-off the flow from the pressure receptacle to that device. The opening through all piping and fittings must have at least the same flow area as the inlet of the pressure relief device to which it is connected. The nominal size of the discharge piping must be at least as large as that of the pressure relief device.
(3) Location of pressure-relief devices: For liquefied gases, each pressure relief device must, under maximum filling conditions, be in communication with the vapor space of the pressure receptacles. The devices, when installed, must be arranged to ensure the escaping vapor is discharged upwards and unrestrictedly to prevent impingement of escaping gas or liquid upon the MEGC, its pressure receptacles or personnel. For flammable, pyrophoric and oxidizing gases, the escaping gas must be directed away from the pressure receptacle in such a manner that it cannot impinge upon the other pressure receptacles. Heat resistant protective devices that deflect the flow of gas are permissible provided the required pressure relief device capacity is not reduced. Arrangements must be made to prevent access to the pressure relief devices by unauthorized persons and to protect the devices from damage caused by rollover.
(g) Gauging devices. When a MEGC is intended to be filled by mass, it must be equipped with one or more gauging devices. Glass level-gauges and gauges made of other fragile material are prohibited.
(h) MEGC supports, frameworks, lifting and tie-down attachments. (1) MEGCs must be designed and constructed with a support structure to provide a secure base during transport. MEGCs must be protected against damage to the pressure receptacles and service equipment resulting from lateral and longitudinal impact and overturning. The forces specified in paragraph (d)(8) of this section, and the safety factor specified in paragraph (d)(10) of this section must be considered in this aspect of the design. Skids, frameworks, cradles or other similar structures are acceptable. If the pressure receptacles and service equipment are so constructed as to withstand impact and overturning, additional protective support structure is not required (see paragraph (h)(4) of this section).
(2) The combined stresses caused by pressure receptacle mountings (e.g. cradles, frameworks, etc.) and MEGC lifting and tie-down attachments must not cause excessive stress in any pressure receptacle. Permanent lifting and tie-down attachments must be equipped to all MEGCs. Any welding of mountings or attachments onto the pressure receptacles is prohibited.
(3) The effects of environmental corrosion must be taken into account in the design of supports and frameworks.
(4) When MEGCs are not protected during transport as specified in paragraph (h)(1) of this section, the pressure receptacles and service equipment must be protected against damage resulting from lateral or longitudinal impact or overturning. External fittings must be protected against release of the pressure receptacles' contents upon impact or overturning of the MEGC on its fittings. Particular attention must be paid to the protection of the manifold. Examples of protection include:
(i) Protection against lateral impact, which may consist of longitudinal bars;
(ii) Protection against overturning, which may consist of reinforcement rings or bars fixed across the frame;
(iii) Protection against rear impact, which may consist of a bumper or frame;
(iv) Protection of the pressure receptacles and service equipment against damage from impact or overturning by use of an ISO frame according to the relevant provisions of ISO 1496-3. (IBR, see § 171.7 of this subchapter).
(i) Initial inspection and test. The pressure receptacles and items of equipment of each MEGC must be inspected and tested before being put into service for the first time (initial inspection and test). This initial inspection and test of an MEGC must include the following:
(1) A check of the design characteristics.
(2) An external examination of the MEGC and its fittings, taking into account the hazardous materials to be transported.
(3) A pressure test performed at the test pressures specified in § 173.304b(b)(1) and (2) of this subchapter. The pressure test of the manifold may be performed as a hydraulic test or by using another liquid or gas. A leakproofness test and a test of the satisfactory operation of all service equipment must also be performed before the MEGC is placed into service. When the pressure receptacles and their fittings have been pressure-tested separately, they must be subjected to a leakproof test after assembly.
(4) An MEGC that meets the definition of “container” in the CSC (see 49 CFR 450.3(a)(2)) must be subjected to an impact test using a prototype representing each design type. The prototype MEGC must be shown to be capable of absorbing the forces resulting from an impact not less than 4 times (4 g) the MPGM of the fully loaded MEGC, at a duration typical of the mechanical shocks experienced in rail transport. A listing of acceptable methods for performing the impact test is provided in the UN Recommendations (IBR, see § 171.7 of this subchapter).
(j) Marking. (1) Each MEGC must be equipped with a corrosion resistant metal plate permanently attached to the MEGC in a conspicuous place readily accessible for inspection. The pressure receptacles must be marked according to this section. Affixing the metal plate to a pressure receptacle is prohibited. At a minimum, the following information must be marked on the plate by stamping or by any other equivalent method:
Stamp of the approval agency who performed or witnessed the most recent test
(2) The following information must be marked on a metal plate firmly secured to the MEGC:
§§ 178.251--178.253-5   [Reserved]
§ 178.255   Specification 60; steel portable tanks.
§ 178.255-1   General requirements.
(a) Tanks must be of fusion welded construction, cylindrical in shape with seamless heads concave to the pressure. Tank shells may be of seamless construction.
(b) Tanks must be designed, constructed, certified, and stamped in accordance with Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter).
(c) Tanks including all permanent attachments must be postweld heat treated as a unit.
(d) Requirements concerning types of valves, retesting, and qualification of portable tanks contained in §§ 173.32 and 173.315 of this chapter must be observed.
§ 178.255-2   Material.
(a) Material used in the tank must be steel of good weldable quality and conform with the requirements in Sections V, VIII, and IX of the ASME Code (IBR, see § 171.7 of this subchapter).
(b) The minimum thickness of metal, exclusive of lining material, for shell and heads of tanks shall be as follows:
§ 178.255-3   Expansion domes.
(a) Expansion domes, if applied, must have a minimum capacity of one percent of the combined capacity of the tank and dome.
(b) [Reserved]
§ 178.255-4   Closures for manholes and domes.
(a) The manhole cover shall be designed to provide a secure closure of the manhole. All covers, not hinged to the tanks, shall be attached to the outside of the dome by at least 1/8 inch chain or its equivalent. Closures shall be made tight against leakage of vapor and liquid by use of gaskets of suitable material.
(b) [Reserved]
§ 178.255-5   Bottom discharge outlets.
(a) Bottom discharge outlets prohibited, except on tanks used for shipments of sludge acid and alkaline corrosive liquids.
(b) If installed, bottom outlets or bottom washout chambers shall be of metal not subject to rapid deterioration by the lading, and each shall be provided with a valve or plug at its upper end and liquid-tight closure at it lower end. Each valve or plug shall be designed to insure against unseating due to stresses or shocks incident to transportation. Bottom outlets shall be adequately protected against handling damage and outlet equipment must not extend to within less than one inch of the bottom bearing surface of the skids or tank mounting.
§ 178.255-6   Loading and unloading accessories.
(a) When installed, gauging, loading and air inlet devices, including their valves, shall be provided with adequate means for their secure closure; and means shall also be provided for the closing of pipe connections of valves.
(b) Interior heater coils, if installed, must be of extra heavy pipe and so constructed that breaking off of exterior connections will not cause leakage of tanks.
§ 178.255-7   Protection of valves and accessories.
(a) All valves, fittings, accessories, safety devices, gauging devices, and the like shall be adequately protected against mechanical damage by a housing closed with a cover plate.
(b) Protective housing shall comply with the requirements under which the tanks are fabricated with respect to design and construction, and shall be designed with a minimum factor of safety of four to withstand loadings in any direction equal to two times the weight of the tank and attachments when filled with water.
§ 178.255-8   Safety devices.
(a) See § 173.315(i) of this subchapter.
(b) [Reserved]
§ 178.255-9   Compartments.
(a) When the interior of the tank is divided into compartments, each compartment shall be designed, constructed and tested as a separate tank. Thickness of shell and compartment heads shall be determined on the basis of total tank capacity.
(b) [Reserved]
§ 178.255-10   Lining.
(a) If a lining is required, the material used for lining the tank shall be homogeneous, nonporous, imperforate when applied, not less elastic than the metal of the tank proper. It shall be of substantially uniform thickness, not less than 1/32 inch thick if metallic, and not less than 1/16 inch thick if nonmetallic, and shall be directly bonded or attached by other equally satisfactory means. Rubber lining shall be not less than 3/16 inch thick. Joints and seams in the lining shall be made by fusing the material together or by other equally satisfactory means. The interior of the tank shall be free from scale, oxidation, moisture and all foreign matter during the lining operation.
(b) [Reserved]
§ 178.255-11   Tank mountings.
(a) Tanks shall be designed and fabricated with mountings to provide a secure base in transit. “Skids” or similar devices shall be deemed to comply with this requirement.
(b) All tank mountings such as skids, fastenings, brackets, cradles, lifting lugs, etc., intended to carry loadings shall be permanently secured to tanks in accordance with the requirements under which the tanks are fabricated, and shall be designed with a factor of safety of four, and built to withstand loadings in any direction equal to two times the weight of the tanks and attachments when filled to the maximum permissible loaded weight.
(c) Lifting lugs or side hold-down lugs shall be provided on the tank mountings in a manner suitable for attaching lifting gear and hold-down devices. Lifting lugs and hold-down lugs welded directly to the tank shall be of the pad-eye type. Doubling plates welded to the tank and located at the points of support shall be deemed to comply with this requirement.
(d) All tank mountings shall be so designed as to prevent the concentration of excessive loads on the tank shell.
§ 178.255-12   Pressure test.
(a) Each completed portable tank prior to application of lining shall be tested before being put into transportation service by completely filling the tank with water or other liquid having a similar viscosity, the temperature of which shall not exceed 100 °F during the test, and applying a pressure of 60 psig. The tank shall be capable of holding the prescribed pressure for at least 10 minutes without leakage, evidence of impending failure, or failure. All closures shall be in place while the test is made and the pressure shall be gauged at the top of the tank. Safety devices and/or vents shall be plugged during this test.
(b) [Reserved]
§ 178.255-13   Repair of tanks.
(a) Tanks failing to meet the test may be repaired and retested, provided that repairs are made in complete compliance with the requirements of this specification.
(b) [Reserved]
§ 178.255-14   Marking.
(a) In addition to markings required by Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter), every tank shall bear permanent marks at least 1/8-inch high stamped into the metal near the center of one of the tank heads or stamped into a plate permanently attached to the tank by means of brazing or welding or other suitable means as follows:
(b) [Reserved]
§ 178.255-15   Report.
(a) A copy of the manufacturer's data report required by Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter) under which the tank is fabricated must be furnished to the owner for each new tank.
It is hereby certified that this tank is in complete compliance with the requirements of DOT specification No. 60.
(b) [Reserved]
§ 178.273   Approval of Specification UN portable tanks.
(a) Application for approval. (1) An owner or manufacturer of a portable tank shall apply for approval to a designated approval agency authorized to approve the portable tank in accordance with the procedures in subpart E, part 107 of this subchapter.
(2) Each application for approval must contain the following information:
(i) Two complete copies of all engineering drawings, calculations, and test data necessary to ensure that the design meets the relevant specification.
(ii) The manufacturer's serial number that will be assigned to each portable tank.
(iii) A statement as to whether the design type has been examined by any approval agency previously and judged unacceptable. Affirmative statements must be documented with the name of the approval agency, reason for nonacceptance, and the nature of modifications made to the design type.
(b) Action by approval agency. The approval agency must perform the following activities:
(1) Review the application for approval to determine whether it is complete and conforms with the requirements of paragraph (a) of this section. If an application is incomplete, it will be returned to the applicant with an explanation as to why the application is incomplete.
(2) Review all drawings and calculations to ensure that the design is in compliance with all requirements of the relevant specification. If the application is approved, one set of the approved drawings, calculations, and test data shall be returned to the applicant. The second (inspector's copy) set of approved drawings, calculations, and test data shall be retained by the approval agency. Maintain drawings and approval records for as long as the portable tank remains in service. The drawings and records must be provided to the Department of Transportation (DOT) upon request.
(3) Witness all tests required for the approval of the portable tank specified in this section and part 180, subpart G of this subchapter.
(4) Ensure, through appropriate inspection that each portable tank is fabricated in all respects in conformance with the approved drawings, calculations, and test data.
(5) Determine and ensure that the portable tank is suitable for its intended use and that it conforms to the requirements of this subchapter.
(6) For UN portable tanks intended for non-refrigerated and refrigerated liquefied gases and Division 6.1 liquids which meet the inhalation toxicity criteria (Zone A or B) as defined in § 173.132 of this subchapter, or that are designated as toxic by inhalation materials in the § 172.101 Table of this subchapter, the approval agency must ensure that:
(i) The portable tank has been designed, constructed, certified, and stamped in accordance with the requirements in Division 1 of Section VIII of the ASME Code (IBR, see § 171.7 of this subchapter). Other design codes may be used if approved by the Associate Administrator (see § 178.274(b)(1));
(ii) All applicable provisions of the design and construction have been met to the satisfaction of the designated approval agency in accordance with the rules established in the ASME Code and that the portable tank meets the requirements of the ASME Code and all the applicable requirements specified in this subchapter;
(iii) The inspector has carried out all the inspections specified by the rules established in the ASME Code; and
(iv) The portable tank is marked with a U stamp code symbol under the authority of the authorized independent inspector.
(7) Upon successful completion of all requirements of this subpart, the approval agency must:
(i) Apply its name, identifying mark or identifying number, and the date upon which the approval was issued, to the metal identification marking plate attached to the portable tank. Any approvals for UN portable tanks authorizing design or construction alternatives (Alternate Arrangements) approved by the Associate Administrator (see § 178.274(a)(2)) must be indicated on the plate as specified in § 178.274(i).
(ii) Issue an approval certificate for each portable tank or, in the case of a series of identical portable tanks manufactured to a single design type, for each series of portable tanks. The approval certificate must include all the information required to be displayed on the metal identification plate required by § 178.274(i). The approval certificate must certify that the approval agency designated to approve the portable tank has approved the portable tank in accordance with the procedures in subpart E of part 107 of this subchapter and that the portable tank is suitable for its intended purpose and meets the requirements of this subchapter. When a series of portable tanks is manufactured without change in the design type, the certificate may be valid for the entire series of portable tanks representing a single design type. For UN portable tanks, the certificate must refer to the prototype test report, the hazardous material or group of hazardous materials allowed to be transported, the materials of construction of the shell and lining (when applicable) and an approval number. The approval number must consist of the distinguishing sign or mark of the country (“USA” for the United States of America) where the approval was granted and a registration number.
(iii) Retain a copy of each approval certificate.
(8) For UN portable tanks, the approval certificate must also include the following:
(i) The results of the applicable framework and rail impact test specified in part 180, subpart G, of this subchapter; and
(ii) The results of the initial inspection and test in § 178.274(j).
(9) The approval agency shall be independent from the manufacturer. The approval agency and the authorized inspector may be the same entity.
(c) Manufacturers' responsibilities. The manufacturer is responsible for compliance with the applicable specifications for the design and construction of portable tanks. In addition to responsibility for compliance, manufacturers are responsible for ensuring that the contracted approval agency and authorized inspector, if applicable, are qualified, reputable and competent. The manufacturer of a portable tank shall—
(1) Comply with all the applicable requirements of the ASME Code and of this subpart including, but not limited to, ensuring that the quality control, design calculations and required tests are performed and that all aspects of the portable tank meet the applicable requirements.
(2) Obtain and use a designated approval agency, if applicable, and obtain and use a DOT-designated approval agency to approve the design, construction and certification of the portable tank.
(3) Provide a statement in the manufacturers' data report certifying that each portable tank that is manufactured complies with the relevant specification and all the applicable requirements of this subchapter.
(4) Maintain records of the qualification of portable tanks for at least 5 years and provide copies to the approval agency, the owner or lessee of the tank. Upon request, provide these records to a representative of DOT.
(d) Denial of application for approval. If an approval agency finds that a portable tank cannot be approved for any reason, it shall notify the applicant in writing and shall provide the applicant with the reasons for which the approval is denied. A copy of the notification letter shall be provided to the Associate Administrator. An applicant aggrieved by a decision of an approval agency may appeal the decision in writing, within 90 days of receipt, to the Associate Administrator.
(e) Modifications to approved portable tanks. (1) Prior to modification of any UN portable tank which may affect conformance and the safe use of the portable tank, which may involve a change to the design type or which may affect its ability to retain hazardous material in transportation, the person desiring to make such modification shall inform the approval agency that issued the initial approval of the portable tank (or if unavailable, another approval agency) of the nature of the modification and request approval of the modification. The person desiring to modify the tank must supply the approval agency with three sets of all revised drawings, calculations, and test data relative to the intended modification.
(2) A statement as to whether the intended modification has been examined and determined to be unacceptable by any approval agency. The written statement must include the name of the approving agency, the reason for nonacceptance, and the nature of changes made to the modification since its original rejection.
(3) The approval agency shall review the request for modification, and if it is determined that the proposed modification is in full compliance with the relevant DOT specification, including a UN portable tank, the request shall be approved and the approval agency shall perform the following activities:
(i) Return one set of the approved revised drawings, calculations, and test data to the applicant. The second and third sets of the approved revised drawings, calculations, and data shall be retained by the approval agency as required in § 107.404(a)(3) of this subchapter.
(ii) Ensure through appropriate inspection that all modifications conform to the revised drawings, calculations, and test data.
(iii) Determine the extent to which retesting of the modified tank is necessary based on the nature of the proposed modification, and ensure that all required retests are satisfactorily performed.
(iv) If modification to an approved tank alters any information on the approval certificate, issue a new approval certificate for the modified tank and ensure that any necessary changes are made to the metal identification plate. A copy of each newly issued approval certificate shall be retained by the approval agency and by the owner of each portable tank.
(4) If the approval agency determines that the proposed modification is not in compliance with the relevant DOT specification, the approval agency shall deny the request in accordance with paragraph (d) of this section.
(f) Termination of Approval Certificate. (1) The Associate Administrator may terminate an approval issued under this section if he determines that—
(i) Information upon which the approval was based is fraudulent or substantially erroneous; or
(ii) Termination of the approval is necessary to adequately protect against risks to life and property; or
(iii) The approval was not issued by the approval agency in good faith; or
(iv) The portable tank does not meet the specification.
(2) Before an approval is terminated, the Associate Administrator gives the interested party(ies):
(i) Written notice of the facts or conduct believed to warrant the termination;
(ii) Opportunity to submit oral and written evidence; and
(iii) Opportunity to demonstrate or achieve compliance with the applicable requirements.
(3) If the Associate Administrator determines that a certificate of approval must be terminated to preclude a significant and imminent adverse affect on public safety, he may terminate the certificate immediately. In such circumstances, the opportunities of paragraphs (f)(2) (ii) and (iii) of this section need not be provided prior to termination of the approval, but shall be provided as soon as practicable thereafter.